mypy

gh-151126: Fix crash on unset memory error in `ctypes.get_errno` (#15… #21869

Job	Run time
Run mypy on Tools/check-c-api-docs	17s
Run mypy on Tools/build	17s
Run mypy on Lib/tomllib	20s
Run mypy on Lib/test/libregrtest	21s
Run mypy on Tools/jit	19s
Run mypy on Tools/peg_generator	18s
Run mypy on Tools/clinic	19s
Run mypy on Tools/cases_generator	19s
Run mypy on Lib/_pyrepl	18s
	2m 48s

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