remove a few mypy excludes

[graingert]

I accidentally read the "If you are seeing this, feel free to create a PR to cover the below files." note and became obligated

Summary

Checklist

• I understand that this PR may be closed in case there was no previous discussion. (This doesn't apply to typos!)
• I've added a test for each change that was introduced, and I tried as much as possible to make a single atomic change.
• I've updated the documentation accordingly.

[Kludex]

Thanks @graingert ! Glad to have you back! 😃