Rebase python-etcd3gw to 0.2.5 in train/el8 testing
Rebase python-etcd3gw to 0.2.5 in train/el8 testing

Includes some required python3 compat fixes.

Change-Id: I3c145f448457ca6c4905f71824a658d63d8ef274
Resolves: rhbz#1804445

redhat-openstack/rdoinfo