mypy

GH-134584: Remove redundant refcount for `BINARY_OP_SUBSCR_STR_INT` (… #9964

Job	Run time
Run mypy on Lib/_pyrepl	18s
Run mypy on Lib/test/libregrtest	20s
Run mypy on Tools/peg_generator	20s
Run mypy on Lib/tomllib	19s
Run mypy on Tools/cases_generator	20s
Run mypy on Tools/check-c-api-docs	18s
Run mypy on Tools/jit	19s
Run mypy on Tools/build	18s
Run mypy on Tools/clinic	12s
	2m 44s

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