Travis stopped handing out free credits since their plan changes last
November, so tests have not run since then.
Cirrus CI offers an API similar to Travis, and also explicitly supports
/dev/kvm access.
Eventually we want to use the cockpit/tasks container directly. But we
can't fix the /dev/kvm permissions inside that as `sudo` does not work
in that. Once we fix that, the setup will become much cheaper and
simpler.
