mypy

gh-146587: fix type slot assignment incase of multiple slots for same… #20264

Job	Run time
Run mypy on Tools/check-c-api-docs	18s
Run mypy on Lib/_pyrepl	17s
Run mypy on Tools/build	17s
Run mypy on Tools/cases_generator	20s
Run mypy on Lib/tomllib	16s
Run mypy on Tools/jit	17s
Run mypy on Lib/test/libregrtest	23s
Run mypy on Tools/peg_generator	20s
Run mypy on Tools/clinic	16s
	2m 44s

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