BUG: Series.str.extract with StringArray returning object dtype
test changes needed in #41372 revealed an issue with the current implementation. fixing for completeness and to add release note.

the dtype for an empty DataFrame from  .str.get_dummies looks iffy so marking this as draft until further investigation.
> the dtype for an empty DataFrame from .str.get_dummies looks iffy so marking this as draft until further investigation.

I can't recall why I originally changed that test in #41372 as there are no columns in the result so the dtype is irrelevant. have removed dtype on the .str.get_dummies test instead. looks good. 