[BE]: Enable some basic pytest style rules (#110362)
Adds some basic flake8-pytest-style rules from ruff with their autofixes. I just picked a couple uncontroversial changes about having a consistent pytest style that were already following. We should consider enabling some more in the future, but this is a good start. I also upgraded ruff to the latest version.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/110362
Approved by: https://github.com/ezyang, https://github.com/albanD, https://github.com/kit1980
