TYP: Fix typing errors on main

- [x] All [code checks passed](https://pandas.pydata.org/pandas-docs/dev/development/contributing_codebase.html#pre-commit).
- [x] Added [type annotations](https://pandas.pydata.org/pandas-docs/dev/development/contributing_codebase.html#type-hints) to new arguments/methods/functions.

slightly off-topic for this PR. but it appears that when the typing validation fails,  "Run docstring validation script tests" is skipped, so have been living dangerously ignoring the ci failures today. Thanks @mroeschke 