mypy

gh-134584: Eliminate redundant refcounting from _STORE_SUBSCR_DICT (G… #18534

Job	Run time
Run mypy on Tools/cases_generator	18s
Run mypy on Lib/test/libregrtest	17s
Run mypy on Lib/tomllib	16s
Run mypy on Tools/build	19s
Run mypy on Tools/jit	21s
Run mypy on Tools/clinic	18s
Run mypy on Tools/peg_generator	17s
Run mypy on Lib/_pyrepl	24s
	2m 30s

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