TST: added test_join_multiindex_dates
- [ ] closes #33692
- [ ] tests added / passed
- [ ] 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

Added tests to make sure that  joining dataframes with multiindices containing dates doesn't break.

This pull request is stale because it has been open for thirty days with no activity. Please update or respond to this comment if you're still interested in working on this. closing as stale, pls ping if you want to continue working.