TST: encoding for URLs in read_csv
- [x] closes #10424
- [x] tests added / passed
- [x] passes `black pandas`
- [x] passes `git diff upstream/master -u -- "*.py" | flake8 --diff`
- [ ] whatsnew entry

Reading CSVs from URLs with a non UTF-8 encoding should already work.
thanks @twoertwein 