DEPR: Change raw kwarg in rolling/expanding.apply to False
- [x] xref #6581
- [x] tests added / passed
- [x] passes `black pandas`
- [x] passes `git diff upstream/master -u -- "*.py" | flake8 --diff`
- [x] whatsnew entry

small comment, not a blocker.  LGTM thanks @mroeschke can you update the deprecations issue as well (move to completed)