mypy

Use the latest dev container image perpetually (#137734) #9482

Job	Run time
Run mypy on Tools/cases_generator	12s
Run mypy on Lib/_pyrepl	16s
Run mypy on Lib/tomllib	17s
Run mypy on Tools/peg_generator	22s
Run mypy on Tools/jit	12s
Run mypy on Tools/build	15s
Run mypy on Lib/test/libregrtest	22s
Run mypy on Tools/clinic	18s
	2m 14s

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