mypy

Revert "gh-66234: Add flag to disable the use of mmap in dbm.gnu (GH-… #9617

Job	Run time
Run mypy on Lib/test/libregrtest	20s
Run mypy on Lib/_pyrepl	18s
Run mypy on Tools/clinic	17s
Run mypy on Tools/jit	25s
Run mypy on Tools/peg_generator	23s
Run mypy on Lib/tomllib	15s
Run mypy on Tools/cases_generator	18s
Run mypy on Tools/build	18s
	2m 34s

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