32380 deprecate squeeze in groupby
- [x] closes #32380
- [x] tests added / passed
- [x] passes `black pandas`
- [x] passes `git diff upstream/master -u -- "*.py" | flake8 --diff`
- [x] whatsnew entry

I deprecated the squeeze keyword. I think I got every points this keyword was used. 
I hope that I considered every point necessary to deprecate a keyword. I tried to use other points were a keyword was deprecated as example.
