Run mypy over test/test_utils.py (#49654)
Summary:
This caught one incorrect annotation in `cpp_extension.load`.
xref gh-16574.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/49654
Reviewed By: heitorschueroff
Differential Revision: D25757691
Pulled By: ezyang
fbshipit-source-id: 145ce3ae532cc585d9ca3bbd5381401bad0072e2
