mypy

Post 3.15.0a3 #18571

Job	Run time
Run mypy on Tools/jit	17s
Run mypy on Tools/build	21s
Run mypy on Tools/clinic	17s
Run mypy on Lib/tomllib	16s
Run mypy on Lib/_pyrepl	22s
Run mypy on Tools/cases_generator	19s
Run mypy on Tools/peg_generator	18s
Run mypy on Lib/test/libregrtest	20s
	2m 30s

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