CLN, TYP use from __future__ import annotations
Seeing as pandas is Python3.7+ we can clean up some annotations. Not yet figured out how to write a good automated check for this, but here's a start
see also #36091 @MarcoGorelli I'll merge this now as without a check it's a waste of valuable reviewer time to check that all quotes are removed from a module when the import is added.

but there we a few here that are obvious without a through check. a separate PR dealing with return types is welcome.