Saving a workbook with richtext enabled gives an error on python > 3.9

When loading, and later saving again a richtext enabled workbook, I get a combination of the following errors (on python 3.10)

  File "C:\...\lib\site-packages\openpyxl\cell\_writer.py", line 82, in etree_write_cell
    text = r.name
AttributeError: 'TextBlock' object has no attribute 'name' 

  File "C:\...\lib\site-packages\openpyxl\xml\functions.py", line 86, in whitespace
    if node.text != node.text.strip():
AttributeError: 'xml.etree.ElementTree.Element' object has no attribute 'strip'

While searching for the issue, I found that others ran into it as well: issue on google groups

I fixed the bug locally, and attached the diff below (I don't know if this is the correct workflow, but I could not find how else to do this, not used to mercurial).

patch.diff