unpin openpyxl
- [x] passes `git diff upstream/master -u -- "*.py" | flake8 --diff`

- Follow up from #22601.

- Confirmed with openpyxl this bug was fixed in version 2.5.7 see [bitbucket issue here](https://bitbucket.org/openpyxl/openpyxl/issues/1093/newly-introduced-keyerror-problem-in)

This was release 13th Sept -> https://pypi.org/project/openpyxl/#history
