Offer to take over openpyxl / request for DM permissions

[Rebecca N. Palmer]

The version of openpyxl currently in Debian is over a year behind 
upstream, and this is blocking the pandas 2.x transition.  I previously 
reported this as #1051233, to no response.  (The package has been 
uploaded more recently than that, but keeping the same upstream version; 
as noted in that bug, it's unclear why.)

Hence, if nobody objects I intend to take over maintenance of this 
package.  I will need either DM permissions or sponsorship to upload it.