mypy

gh-139076: Fix regression in pydoc not showing extension functions (G… #16863

Job	Run time
Run mypy on Tools/cases_generator	21s
Run mypy on Tools/jit	20s
Run mypy on Lib/test/libregrtest	17s
Run mypy on Lib/_pyrepl	23s
Run mypy on Tools/peg_generator	18s
Run mypy on Tools/clinic	21s
Run mypy on Lib/tomllib	20s
Run mypy on Tools/build	21s
	2m 41s

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