mypy

gh-144380: Fix incorrect type check in `buffered_iternext()` (#144381) #19348

Job	Run time
Run mypy on Tools/build	20s
Run mypy on Lib/tomllib	16s
Run mypy on Tools/check-c-api-docs	18s
Run mypy on Lib/_pyrepl	20s
Run mypy on Tools/cases_generator	18s
Run mypy on Tools/peg_generator	19s
Run mypy on Lib/test/libregrtest	17s
Run mypy on Tools/jit	19s
Run mypy on Tools/clinic	20s
	2m 47s

Provide feedback