mypy

gh-80744: do not read .pdbrc twice when cwd == $home (#136816) #9975

Job	Run time
Run mypy on Tools/cases_generator	16s
Run mypy on Tools/build	18s
Run mypy on Tools/clinic	19s
Run mypy on Tools/check-c-api-docs	19s
Run mypy on Lib/_pyrepl	18s
Run mypy on Lib/test/libregrtest	19s
Run mypy on Lib/tomllib	19s
Run mypy on Tools/peg_generator	18s
Run mypy on Tools/jit	20s
	2m 46s

Provide feedback