black 21.8b0 on Python PyPI

Add support for formatting Jupyter Notebook files (#2357)
Move from appdirs dependency to platformdirs (#2375)
Present a more user-friendly error if .gitignore is invalid (#2414)
The failsafe for accidentally added backslashes in f-string expressions has been hardened to handle more edge cases during quote normalization (#2437)
Avoid changing a function return type annotation's type to a tuple by adding a trailing comma (#2384)
Parsing support has been added for unparenthesized walruses in set literals, set comprehensions, and indices (#2447).
Pin setuptools-scm build-time dependency version (#2457)
Exclude typing-extensions version 3.10.0.1 due to it being broken on Python 3.10 (#2460)

Replace sys.exit(-1) with raise ImportError as it plays more nicely with tools that scan installed packages (#2440)

The provided pre-commit hooks no longer specify language_version to avoid overriding default_language_version (#2430)