mypy

gh-138970: Add general metadata system to the peg generator (#138971) #9607

Job	Run time
Run mypy on Lib/test/libregrtest	19s
Run mypy on Tools/jit	22s
Run mypy on Lib/tomllib	19s
Run mypy on Tools/cases_generator	18s
Run mypy on Tools/peg_generator	22s
Run mypy on Tools/build	18s
Run mypy on Tools/clinic	18s
Run mypy on Lib/_pyrepl	23s
	2m 39s

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