mypy

gh-140729: Add __mp_main as a duplicate for main__ for pickle to … #18004

Job	Run time
Run mypy on Lib/tomllib	17s
Run mypy on Lib/_pyrepl	18s
Run mypy on Lib/test/libregrtest	19s
Run mypy on Tools/clinic	17s
Run mypy on Tools/build	19s
Run mypy on Tools/jit	20s
Run mypy on Tools/cases_generator	17s
Run mypy on Tools/peg_generator	27s
	2m 34s

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