21.12b0

Black

• Fix determination of f-string expression spans (#2654)
• Fix bad formatting of error messages about EOF in multi-line statements (#2343)
• Functions and classes in blocks now have more consistent surrounding spacing (#2472)

Jupyter Notebook support

• Cell magics are now only processed if they are known Python cell magics. Earlier, all cell magics were tokenized, leading to possible indentation errors e.g. with %%writefile. (#2630)
• Fix assignment to environment variables in Jupyter Notebooks (#2642)

Python 3.10 support

• Point users to using --target-version py310 if we detect 3.10-only syntax (#2668)
• Fix match statements with open sequence subjects, like match a, b: or match a, *b: (#2639) (#2659)
• Fix match/case statements that contain match/case soft keywords multiple times, like match re.match() (#2661)
• Fix case statements with an inline body (#2665)
• Fix styling of starred expressions inside match subject (#2667)
• Fix parser error location on invalid syntax in a match statement (#2649)
• Fix Python 3.10 support on platforms without ProcessPoolExecutor (#2631)
• Improve parsing performance on code that uses match under --target-version py310 up to ~50% (#2670)

Packaging

• Remove dependency on regex (#2644) (#2663)

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Thank you!

• @isidentical for the polishing up 3.10 syntax support (which they contributed in the first place!)
• @MarcoGorelli for their ever-continuing work on Black's jupyter support
• @jalaziz for cleaning up our Pyinstaller CD workflow
• @hauntsaninja for helping us drop the regex dependency

And also congrats to first contributors!

• @MatthewScholefield made their first contribution in #2631
• @AshIsbitt made their first contribution in #2632
• @kalbasit made their first contribution in #2638
• @danieleades made their first contribution in #2653
• @danielsparing made their first contribution in #2630
• @tanvimoharir made their first contribution in #2343