mypy

gh-100239: Propagate type info through _BINARY_OP_EXTEND in tier 2 (G… #20452

Job	Run time
Run mypy on Tools/cases_generator	19s
Run mypy on Tools/jit	18s
Run mypy on Lib/_pyrepl	20s
Run mypy on Tools/clinic	16s
Run mypy on Tools/build	17s
Run mypy on Lib/test/libregrtest	17s
Run mypy on Lib/tomllib	17s
Run mypy on Tools/check-c-api-docs	18s
Run mypy on Tools/peg_generator	17s
	2m 39s

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