mypy

gh-125895: Fix static asset location for `sphinx-notfound-page` (#147… #20377

Job	Run time
Run mypy on Tools/clinic	19s
Run mypy on Lib/test/libregrtest	20s
Run mypy on Tools/peg_generator	17s
Run mypy on Tools/build	22s
Run mypy on Lib/tomllib	19s
Run mypy on Tools/jit	20s
Run mypy on Lib/_pyrepl	16s
Run mypy on Tools/cases_generator	20s
Run mypy on Tools/check-c-api-docs	17s
	2m 50s

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