BUG: fix reindexing with a tz-aware index and method='nearest'
- [x] closes #26683
- [x] tests added / passed
- [x] passes `black pandas`
- [x] passes `git diff upstream/master -u -- "*.py" | flake8 --diff`
- [x] whatsnew entry

First pandas PR, happy to make changes as needed.  Is a whatsnew entry needed?  And if so, I assume it should go in v1.0.1.rst? 