ci: unfreeze kernel

The loopback issue should be fixed now and we need a newer kernel for
the rootfs reprovisioning tests to work.

Closes: coreos/fedora-coreos-tracker#619

.cci.jenkinsfile

@@ -14,10 +14,6 @@ cosaPod(buildroot: true) {
             mkdir -p /srv/fcos && cd /srv/fcos
             cosa init https://github.com/coreos/fedora-coreos-config
             mkdir -p overrides/rpm && cd overrides/rpm
-            # freeze kernel to 5.6.7 for now to avoid a regression in loopback
-            # code which interferes with blackbox testing
-            # https://bugs.archlinux.org/task/66526
-            curl -L --remote-name-all https://kojipkgs.fedoraproject.org//packages/kernel/5.6.7/200.fc31/x86_64/kernel{,-core,-modules}-5.6.7-200.fc31.x86_64.rpm
         """)
         fcosBuild(skipInit: true, make: true, skipKola: true)
     }