mypy

gh-148653: Fix reference leaks in test_marshal introduced in gh-14869… #10443

Job	Run time
Run mypy on Tools/build	17s
Run mypy on Lib/test/libregrtest	19s
Run mypy on Tools/check-c-api-docs	18s
Run mypy on Tools/jit	22s
Run mypy on Lib/tomllib	18s
Run mypy on Tools/clinic	21s
Run mypy on Tools/cases_generator	14s
Run mypy on Lib/_pyrepl	22s
Run mypy on Tools/peg_generator	17s
	2m 48s

Provide feedback