mypy

gh-149879: Fix test_grp on Cygwin (#150495) #21585

Job	Run time
Run mypy on Lib/_pyrepl	18s
Run mypy on Lib/tomllib	20s
Run mypy on Tools/peg_generator	19s
Run mypy on Tools/check-c-api-docs	17s
Run mypy on Tools/jit	22s
Run mypy on Tools/clinic	20s
Run mypy on Tools/build	17s
Run mypy on Tools/cases_generator	16s
Run mypy on Lib/test/libregrtest	17s
	2m 46s

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