mypy

gh-127146: Emscripten: Fix test_open_undecodable_uri by setting `-sTE… #15700

Job	Run time
Run mypy on Lib/tomllib	18s
Run mypy on Lib/_pyrepl	17s
Run mypy on Tools/build	14s
Run mypy on Tools/jit	17s
Run mypy on Tools/cases_generator	19s
Run mypy on Tools/peg_generator	17s
Run mypy on Lib/test/libregrtest	22s
Run mypy on Tools/clinic	16s
	2m 20s

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