BUG: Fix mixed datetime dtype inference
- [x] closes #33741
- [x] tests added / passed
- [x] passes `black pandas`
- [x] passes `git diff upstream/master -u -- "*.py" | flake8 --diff`
- [x] whatsnew entry

is the docbuild failure real or a fluke? > is the docbuild failure real or a fluke?

~It looks like something in user_guide/computation.rst which doesn't seem related, kicking off again to check~

Nevermind, was a typo in whatsnew that caused it needs a rebase as well @jreback ping