Fix #28552 Add test for DataFrame min/max preserve timezone
- [x] closes #28552
- [x] tests added / passed
- [x] passes `black pandas`
- [x] passes `git diff upstream/master -u -- "*.py" | flake8 --diff`
- [ ] whatsnew entry _(not applicable - no functionality added)_

Here's a test discussed in #28552. `mean` and other aggregates except for `min` and `max` are not covered since they don't support datetimes - it's a nan being returned.
