mypy

gh-145376: Fix refleak in unusual error path in BaseExceptionGroup_ne… #10242

Job	Run time
Run mypy on Tools/cases_generator	21s
Run mypy on Lib/test/libregrtest	22s
Run mypy on Tools/check-c-api-docs	28s
Run mypy on Tools/build	21s
Run mypy on Lib/_pyrepl	18s
Run mypy on Tools/peg_generator	18s
Run mypy on Lib/tomllib	18s
Run mypy on Tools/clinic	17s
Run mypy on Tools/jit	19s
	3m 2s

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