BUG: tz_localize needs to invalidate freq
- [x] closes #30511
- [x] tests added / passed
- [x] passes `black pandas`
- [x] passes `git diff upstream/master -u -- "*.py" | flake8 --diff`
- [x] whatsnew entry

Identified when trying to add `freq` check to `assert_index_equal` for DatetimeIndex and TimedeltaIndex.
Think this would close https://github.com/pandas-dev/pandas/issues/30511

Also what about tz_convert? > Also what about tz_convert?

I'm pretty sure that for Tick-like freqs, tz_convert should always retain freq.  Others are going to be trickier. Yes, closes #30511 yep thanks. can `tz_convert` change freq? (I think no) > can tz_convert change freq? (I think no)

I'm pretty sure that for Tick-like freqs, tz_convert should always retain freq. Others are going to be trickier.