The new fedora-repo-zdicts-2309.1-1.fc38 update has f39 zchunk
dictionaries, which should make the zchunk deltas better for f39.
I'd like to update compose-branched01/compose-rawhide01/compose-x86_01
so we can get this advantage.
I think this is a pretty low impact change and we can always just back
out to the older version if something happens.