BUG: Series.mode with dt64tz or PeriodDtype
- [x] closes #41927
- [x] tests added / passed
- [x] Ensure all linting tests pass, see [here](https://pandas.pydata.org/pandas-docs/dev/development/contributing_codebase.html#pre-commit) for how to run them
- [x] whatsnew entry

Sits on top of #44581
i ithink this needs a rebase as merged the underlying PR Rebased +greenish