mypy

gh-143054: Disallow non-top-level Cut for now #18983

Job	Run time
Run mypy on Lib/test/libregrtest	17s
Run mypy on Tools/check-c-api-docs	17s
Run mypy on Tools/peg_generator	17s
Run mypy on Tools/build	20s
Run mypy on Lib/tomllib	15s
Run mypy on Tools/jit	19s
Run mypy on Lib/_pyrepl	20s
Run mypy on Tools/clinic	18s
Run mypy on Tools/cases_generator	16s
	2m 39s

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