BUG: Fix interpolate ValueError for datetime64_tz index

- [ x ] closes #27548 
- [ x ] tests added / passed
- [ x ] passes `black pandas`
- [ x ] passes `git diff upstream/master -u -- "*.py" | flake8 --diff`
- [ x ] whatsnew entry

looks ok, ping when changed & green. @jreback I've updated to use the tz_naive_fixture and checks are green thanks @alorenzo175 