To string with encoding
- [x] close #28766
- [x] tests added / passed
- [x] passes `black pandas`
- [x] passes `git diff upstream/master -u -- "*.py" | flake8 --diff`
- [x] whatsnew entry

can you merge master @simonjayhawkins  please have a look. Hi the CI is failing for reasons I do not understand. https://travis-ci.org/pandas-dev/pandas/jobs/600239741 
It says 

> No output has been received in the last 10m0s, this potentially indicates a stalled build or something wrong with the build itself Hi @WillAyd @jreback can you please review. lgtm. merge when @WillAyd and @simonjayhawkins good. @WillAyd updated the branch with the required changes, please have a look. Thanks @farziengineer  Thanks @simonjayhawkins  @WillAyd for all the reviews. 