mypy

gh-145244: Fix use-after-free on borrowed dict key in json encoder (G… #20631

Job	Run time
Run mypy on Lib/test/libregrtest	16s
Run mypy on Lib/tomllib	14s
Run mypy on Lib/_pyrepl	20s
Run mypy on Tools/check-c-api-docs	15s
Run mypy on Tools/cases_generator	17s
Run mypy on Tools/build	16s
Run mypy on Tools/peg_generator	19s
Run mypy on Tools/jit	16s
Run mypy on Tools/clinic	19s
	2m 32s

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