[MNT]: Any type hint in subplots

### Summary

I noticed that type inference in vscode didn't work as expected anymore after updating to 3.8.0 from 3.7.3.  I tracked it down to that the type hint for the output of subplots() is tuple[Figure, Any] and the ax output didn't get proper intellisense in the IDE.


### Proposed fix

Shouldn't the type hint for the output be something like ```tuple[Figure, Axes | list[Axes]]```?
