mypy

gh-134584: Remove redundant refcount from _BINARY_OP_ADD_UNICODE (gh-… #18648

Job	Run time
Run mypy on Lib/_pyrepl	18s
Run mypy on Tools/check-c-api-docs	19s
Run mypy on Lib/test/libregrtest	18s
Run mypy on Tools/build	18s
Run mypy on Lib/tomllib	16s
Run mypy on Tools/peg_generator	18s
Run mypy on Tools/cases_generator	21s
Run mypy on Tools/jit	22s
Run mypy on Tools/clinic	19s
	2m 49s

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