DOC: remove references to dev.pandas.io
- [ ] xref #39368 
- [x] tests added / passed
- [x] Ensure all linting tests pass, see [here](https://pandas.pydata.org/pandas-docs/dev/development/contributing.html#code-standards) for how to run them
- [x] whatsnew entry


Suggested fix 

- [x] Remove references to dev.pandas.io
- [ ] Ensure all content from http://dev.pandas.io/pandas-blog/ is on https://pandas.pydata.org/community/blog/
https://github.com/pandas-dev/pandas-blog/tree/master/content
https://github.com/pandas-dev/pandas/tree/master/web/pandas/community/blog
- [ ] Redirect dev.pandas.io