mypy

Fail on new UB in CI #20459

Job	Run time
Run mypy on Tools/clinic	16s
Run mypy on Tools/jit	21s
Run mypy on Tools/build	18s
Run mypy on Lib/_pyrepl	19s
Run mypy on Tools/cases_generator	18s
Run mypy on Tools/peg_generator	25s
Run mypy on Tools/check-c-api-docs	15s
Run mypy on Lib/tomllib	18s
Run mypy on Lib/test/libregrtest	20s
	2m 50s

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