Comment 13 for bug 1806111

To get cinder to to manage the upgrade from python2 to python3 in environments where purestorage is in use the following patches were needed:

https://review.opendev.org/c/openstack/charm-cinder-purestorage/+/782762
https://review.opendev.org/c/openstack/charms.openstack/+/781487
https://review.opendev.org/c/openstack/charm-interface-cinder-backend/+/782761

All 3 of them merged, so I'm marking the task for cinder as "fix committed".