mypy

gh-136567: Add information about lost prefixes to `Tools/cases_genera… #9445

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

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