mypy

gh-146102: Fix type slot_bf_getbuffer() error handling (#151346) #21907

Job	Run time
Run mypy on Lib/test/libregrtest	21s
Run mypy on Tools/check-c-api-docs	21s
Run mypy on Lib/_pyrepl	18s
Run mypy on Tools/build	22s
Run mypy on Tools/cases_generator	20s
Run mypy on Tools/clinic	19s
Run mypy on Lib/tomllib	13s
Run mypy on Tools/peg_generator	21s
Run mypy on Tools/jit	19s
	2m 54s

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