mypy

Fail on new UB in CI #20457

Job	Run time
Run mypy on Lib/tomllib	16s
Run mypy on Lib/test/libregrtest	22s
Run mypy on Tools/peg_generator	16s
Run mypy on Lib/_pyrepl	15s
Run mypy on Tools/check-c-api-docs	18s
Run mypy on Tools/clinic	21s
Run mypy on Tools/build	15s
Run mypy on Tools/jit	18s
Run mypy on Tools/cases_generator	17s
	2m 38s

Provide feedback