ci: Update Docker packages
This would fix !1255 (merged)
but requires waiting for https://bodhi.fedoraproject.org/updates/FEDORA-2019-e830287661 to get into stable (6 days when this MR is filed), or cheating a little and using --enablerepo=updates-testing
on the first dnf install
command when generating the docker image locally.
Edited by Bastien Nocera