mypy

Docs: remove unmatched parenthesis for `asyncio.TaskGroup` note (#146… #19992

Job	Run time
Run mypy on Tools/peg_generator	28s
Run mypy on Tools/build	23s
Run mypy on Tools/check-c-api-docs	19s
Run mypy on Tools/clinic	19s
Run mypy on Lib/tomllib	17s
Run mypy on Lib/_pyrepl	20s
Run mypy on Lib/test/libregrtest	18s
Run mypy on Tools/cases_generator	18s
Run mypy on Tools/jit	21s
	3m 3s

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