[3.10] Match formatting does not support multiple value

[titouanfreville]

Hello and thanks for this library and the reactivity to support python 3.10 new syntaxes.

Describe the bug

While running with the latest version (gotten from git),basic match on a single pattern is correctly supported <3
But it seems that it does not support multiple match value.

I tried on a simple example after observing it on my real code:

To Reproduce

a = 11
b = 12

match a, b:
    case _, 5:
        print("a5")
    case 11, 12:
        print("default")
    case _:
        print("badass")

Should be able to parse. It runs correctly:

python test_black.py 
default

But black fails :'(

black --target-version py310  test_black.py
error: cannot format test_black.py: Cannot parse: 4:6: match a, b:
Oh no! 💥 💔 💥
1 file failed to reformat.

Expected behavior

Should format without errors

Environment

• Black's version: black, 21.11b2.dev3+g4075944 (compiled: no)
• OS and Python version: Linux[DevContainer]/3.10

Additional context

[titouanfreville]

Thanks for the fix <3