mypy

gh-143732: add specialization for `FOR_ITER` #21085

Job	Run time
Run mypy on Lib/_pyrepl	20s
Run mypy on Tools/clinic	18s
Run mypy on Tools/check-c-api-docs	12s
Run mypy on Tools/build	19s
Run mypy on Tools/cases_generator	34s
Run mypy on Lib/test/libregrtest	14s
Run mypy on Lib/tomllib	19s
Run mypy on Tools/jit	15s
Run mypy on Tools/peg_generator	15s
	2m 46s

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