mypy

gh-141489: Simplify closure/freevar iteration in `annotationlib._buil… #18064

Job	Run time
Run mypy on Tools/cases_generator	25s
Run mypy on Lib/test/libregrtest	22s
Run mypy on Lib/_pyrepl	19s
Run mypy on Tools/build	18s
Run mypy on Tools/peg_generator	18s
Run mypy on Tools/jit	16s
Run mypy on Lib/tomllib	12s
Run mypy on Tools/clinic	17s
	2m 27s

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