What's Changed

• Improve Python version and OS compatibility, fixing deprecations by @EliahKagan in #1654
• Better document env_case test/fixture and cwd by @EliahKagan in #1657
• Remove spurious executable permissions by @EliahKagan in #1658
• Fix up checks in Makefile and make them portable by @EliahKagan in #1661
• Fix URLs that were redirecting to another license by @EliahKagan in #1662
• Assorted small fixes/improvements to root dir docs by @EliahKagan in #1663
• Use venv instead of virtualenv in test_installation by @EliahKagan in #1664
• Omit py_modules in setup by @EliahKagan in #1665
• Don't track code coverage temporary files by @EliahKagan in #1666
• Configure tox by @EliahKagan in #1667
• Format tests with black and auto-exclude untracked paths by @EliahKagan in #1668
• Upgrade and broaden flake8, fixing style problems and bugs by @EliahKagan in #1673
• Fix rollback bug in SymbolicReference.set_reference by @EliahKagan in #1675
• Remove @NoEffect annotations by @EliahKagan in #1677
• Add more checks for the validity of refnames by @facutuesca in #1672

Full Changelog: 3.1.36...3.1.37