This release increases log's MSRV from 1.61.0 to 1.68.0.

• docs: Add missing impls from README.md by @AldaronLau in https://github.com/rust-lang/log/pull/703
• Point to new URLs for favicon and logo by @AldaronLau in https://github.com/rust-lang/log/pull/704
• perf: reduce llvm-lines of FromStr for Level and LevelFilter by @dishmaker in https://github.com/rust-lang/log/pull/709
• Replace serde with serde_core by @Thomasdezeeuw in https://github.com/rust-lang/log/pull/712
• Fix clippy lints by @Thomasdezeeuw in https://github.com/rust-lang/log/pull/713
• Use GitHub Actions to install Rust and cargo-hack by @Thomasdezeeuw in https://github.com/rust-lang/log/pull/715
• Exclude old unstable_kv features from testing matrix by @Thomasdezeeuw in https://github.com/rust-lang/log/pull/716
• Fix up CI by @KodrAus in https://github.com/rust-lang/log/pull/718
• Prepare for 0.4.29 release by @KodrAus in https://github.com/rust-lang/log/pull/719

• @AldaronLau made their first contribution in https://github.com/rust-lang/log/pull/703
• @dishmaker made their first contribution in https://github.com/rust-lang/log/pull/709

Full Changelog: https://github.com/rust-lang/log/compare/0.4.28...0.4.29

• ci: drop really old trick and ensure MSRV for all feature combo by @tisonkun in https://github.com/rust-lang/log/pull/676
• chore: fix some typos in comment by @xixishidibei in https://github.com/rust-lang/log/pull/677
• Unhide #[derive(Debug)] in example by @ZylosLumen in https://github.com/rust-lang/log/pull/688
• Chore: delete compare_exchange method for AtomicUsize on platforms without atomics by @HaoliangXu in https://github.com/rust-lang/log/pull/690
• Add increment_severity() and decrement_severity() methods for Level and LevelFilter by @nebkor in https://github.com/rust-lang/log/pull/692
• Prepare for 0.4.28 release by @KodrAus in https://github.com/rust-lang/log/pull/695

• @xixishidibei made their first contribution in https://github.com/rust-lang/log/pull/677
• @ZylosLumen made their first contribution in https://github.com/rust-lang/log/pull/688
• @HaoliangXu made their first contribution in https://github.com/rust-lang/log/pull/690
• @nebkor made their first contribution in https://github.com/rust-lang/log/pull/692

Full Changelog: https://github.com/rust-lang/log/compare/0.4.27...0.4.28

• A few minor lint fixes by @nyurik in https://github.com/rust-lang/log/pull/671
• Enable clippy support for format-like macros by @nyurik in https://github.com/rust-lang/log/pull/665
• Add an optional logger param by @tisonkun in https://github.com/rust-lang/log/pull/664
• Pass global logger by value, supplied logger by ref by @KodrAus in https://github.com/rust-lang/log/pull/673
• Prepare for 0.4.27 release by @KodrAus in https://github.com/rust-lang/log/pull/674

Full Changelog: https://github.com/rust-lang/log/compare/0.4.26...0.4.27

• Derive Clone for kv::Value by @SpriteOvO in https://github.com/rust-lang/log/pull/668
• Add spdlog-rs link to crate doc by @SpriteOvO in https://github.com/rust-lang/log/pull/669
• Prepare for 0.4.26 release by @KodrAus in https://github.com/rust-lang/log/pull/670

Full Changelog: https://github.com/rust-lang/log/compare/0.4.25...0.4.26

• Revert loosening of kv cargo features by @KodrAus in https://github.com/rust-lang/log/pull/662
• Prepare for 0.4.25 release by @KodrAus in https://github.com/rust-lang/log/pull/663

Full Changelog: https://github.com/rust-lang/log/compare/0.4.24...0.4.25

• Fix up kv feature activation by @KodrAus in https://github.com/rust-lang/log/pull/659
• Prepare for 0.4.24 release by @KodrAus in https://github.com/rust-lang/log/pull/660

Full Changelog: https://github.com/rust-lang/log/compare/0.4.23...0.4.24

• Fix some typos by @Kleinmarb in https://github.com/rust-lang/log/pull/637
• Add logforth to implementation by @tisonkun in https://github.com/rust-lang/log/pull/638
• Add spdlog-rs link to README by @SpriteOvO in https://github.com/rust-lang/log/pull/639
• Add correct lifetime to kv::Value::to_borrowed_str by @stevenroose in https://github.com/rust-lang/log/pull/643
• docs: Add logforth as an impl by @tisonkun in https://github.com/rust-lang/log/pull/642
• Add clang_log implementation by @DDAN-17 in https://github.com/rust-lang/log/pull/646
• Bind lifetimes of &str returned from Key by the lifetime of 'k rather than the lifetime of the Key struct by @gbbosak in https://github.com/rust-lang/log/pull/648 (reverted)
• Fix up key lifetimes and add method to try get a borrowed key by @KodrAus in https://github.com/rust-lang/log/pull/653
• Add Ftail implementation by @tjardoo in https://github.com/rust-lang/log/pull/652
• Relax feature flag for value's std_support by @tisonkun in https://github.com/rust-lang/log/pull/657
• Prepare for 0.4.23 release by @KodrAus in https://github.com/rust-lang/log/pull/656

• @Kleinmarb made their first contribution in https://github.com/rust-lang/log/pull/637
• @tisonkun made their first contribution in https://github.com/rust-lang/log/pull/638
• @SpriteOvO made their first contribution in https://github.com/rust-lang/log/pull/639
• @stevenroose made their first contribution in https://github.com/rust-lang/log/pull/643
• @DDAN-17 made their first contribution in https://github.com/rust-lang/log/pull/646
• @gbbosak made their first contribution in https://github.com/rust-lang/log/pull/648
• @tjardoo made their first contribution in https://github.com/rust-lang/log/pull/652

Full Changelog: https://github.com/rust-lang/log/compare/0.4.22...0.4.23

• Add some clarifications to the library docs by @KodrAus in https://github.com/rust-lang/log/pull/620
• Add links to colog crate by @chrivers in https://github.com/rust-lang/log/pull/621
• adding line_number test + updating some testing infrastructure by @DIvkov575 in https://github.com/rust-lang/log/pull/619
• Clarify the actual set of functions that can race in _racy variants by @KodrAus in https://github.com/rust-lang/log/pull/623
• Replace deprecated std::sync::atomic::spin_loop_hint() by @Catamantaloedis in https://github.com/rust-lang/log/pull/625
• Check usage of max_level features by @Thomasdezeeuw in https://github.com/rust-lang/log/pull/627
• Remove unneeded import by @Thomasdezeeuw in https://github.com/rust-lang/log/pull/628
• Loosen orderings for logger initialization in https://github.com/rust-lang/log/pull/632. Originally by @pwoolcoc in https://github.com/rust-lang/log/pull/599
• Use Location::caller() for file and line info in https://github.com/rust-lang/log/pull/633. Originally by @Cassy343 in https://github.com/rust-lang/log/pull/520

• @chrivers made their first contribution in https://github.com/rust-lang/log/pull/621
• @DIvkov575 made their first contribution in https://github.com/rust-lang/log/pull/619
• @Catamantaloedis made their first contribution in https://github.com/rust-lang/log/pull/625

Full Changelog: https://github.com/rust-lang/log/compare/0.4.21...0.4.22

• Minor clippy nits by @nyurik in https://github.com/rust-lang/log/pull/578
• Simplify Display impl by @nyurik in https://github.com/rust-lang/log/pull/579
• Set all crates to 2021 edition by @nyurik in https://github.com/rust-lang/log/pull/580
• Various changes based on review by @Thomasdezeeuw in https://github.com/rust-lang/log/pull/583
• Fix typo in file_static() method doc by @dimo414 in https://github.com/rust-lang/log/pull/590
• Specialize empty key value pairs by @EFanZh in https://github.com/rust-lang/log/pull/576
• Fix incorrect lifetime in Value::to_str() by @peterjoel in https://github.com/rust-lang/log/pull/587
• Remove some API of the key-value feature by @Thomasdezeeuw in https://github.com/rust-lang/log/pull/585
• Add logcontrol-log and log-reload by @swsnr in https://github.com/rust-lang/log/pull/595
• Add Serialization section to kv::Value docs by @Thomasdezeeuw in https://github.com/rust-lang/log/pull/593
• Rename Value::to_str to to_cow_str by @Thomasdezeeuw in https://github.com/rust-lang/log/pull/592
• Clarify documentation and simplify initialization of STATIC_MAX_LEVEL by @ptosi in https://github.com/rust-lang/log/pull/594
• Update docs to 2021 edition, test by @nyurik in https://github.com/rust-lang/log/pull/577
• Add "alterable_logger" link to README.md by @brummer-simon in https://github.com/rust-lang/log/pull/589
• Normalize line ending by @EFanZh in https://github.com/rust-lang/log/pull/602
• Remove ok_or in favor of Option::ok_or by @AngelicosPhosphoros in https://github.com/rust-lang/log/pull/607
• Use Acquire ordering for initialization check by @AngelicosPhosphoros in https://github.com/rust-lang/log/pull/610
• Get structured logging API ready for stabilization by @KodrAus in https://github.com/rust-lang/log/pull/613
• Prepare for 0.4.21 release by @KodrAus in https://github.com/rust-lang/log/pull/617

• @nyurik made their first contribution in https://github.com/rust-lang/log/pull/578
• @dimo414 made their first contribution in https://github.com/rust-lang/log/pull/590
• @peterjoel made their first contribution in https://github.com/rust-lang/log/pull/587
• @ptosi made their first contribution in https://github.com/rust-lang/log/pull/594
• @brummer-simon made their first contribution in https://github.com/rust-lang/log/pull/589
• @AngelicosPhosphoros made their first contribution in https://github.com/rust-lang/log/pull/607

Full Changelog: https://github.com/rust-lang/log/compare/0.4.20...0.4.21

• Remove rustversion dev-dependency by @Thomasdezeeuw in https://github.com/rust-lang/log/pull/568
• Remove local_inner_macros usage by @EFanZh in https://github.com/rust-lang/log/pull/570
• Group target_module, path and file arguments by @EFanZh in https://github.com/rust-lang/log/pull/575
• doc: Add log-to-defmt to other-facilities section by @chrysn in https://github.com/rust-lang/log/pull/574

• @EFanZh made their first contribution in https://github.com/rust-lang/log/pull/570
• @chrysn made their first contribution in https://github.com/rust-lang/log/pull/574

Full Changelog: https://github.com/rust-lang/log/compare/0.4.19...0.4.20