mypy

gh-149879: Fix test_math and test_statistics on Cygwin (#150432) #21569

Job	Run time
Run mypy on Tools/clinic	20s
Run mypy on Lib/tomllib	17s
Run mypy on Tools/check-c-api-docs	16s
Run mypy on Lib/_pyrepl	17s
Run mypy on Tools/cases_generator	21s
Run mypy on Tools/jit	17s
Run mypy on Tools/build	18s
Run mypy on Lib/test/libregrtest	17s
Run mypy on Tools/peg_generator	17s
	2m 40s

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