Unpin openpyxl
I *think* we pinned this originally because of issues with 3.0.2 specifically, but looks like a newer version is available on conda

ref #30009
Could this become !=3.0.1 so we retain the knowledge that this one version is not supported Thought about that but we don't do that for other packages do we? fair enough.  LGTM cc @datapythonista thoughts? thanks @WillAyd 