STY: concat strings that should not be seperated
- [ ] closes #xxxx
- [ ] tests added / passed
- [x] passes `black pandas`
- [x] passes `git diff upstream/master -u -- "*.py" | flake8 --diff`
- [ ] whatsnew entry

>  best in general to leave cython files untouched and wait for black to support formatting cython.

@simonjayhawkins should I close this PR then?
 > > best in general to leave cython files untouched and wait for black to support formatting cython.
> 
> @simonjayhawkins should I close this PR then?

I think OK to merge this once the changed message https://github.com/pandas-dev/pandas/pull/30942#discussion_r365592016 is reverted ping @simonjayhawkins  Thanks @MomIsBestFriend 