Deprecate inplace in Categorical.rename_categories
- [x] xref #37643
- [x] tests added / passed
- [x] passes `black pandas`
- [x] passes `git diff upstream/master -u -- "*.py" | flake8 --diff`
- [x] whatsnew entry

need to do `tm.assert_produces_warning` in some of the existing tests i think > need to do `tm.assert_produces_warning` in some of the existing tests i think

As far as I see, the failed CI task treats warnings as errors. I will check which tests should be changed yeah pls assert the warning o nthe failing tests and ping on green @jbrockmendel @jreback 
I fixed the uncaught warning issues, all checks are green. thanks @OlehKSS 