mypy

gh-150988: Fix refleak in `OSError` when attrs are set before `super(… #21814

Job	Run time
Run mypy on Tools/cases_generator	19s
Run mypy on Tools/build	21s
Run mypy on Lib/tomllib	22s
Run mypy on Tools/check-c-api-docs	19s
Run mypy on Tools/peg_generator	22s
Run mypy on Lib/_pyrepl	19s
Run mypy on Tools/clinic	20s
Run mypy on Tools/jit	22s
Run mypy on Lib/test/libregrtest	22s
	3m 6s

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