0.12.8

Use urandom instead random for rng backend device

As per upstream docs https://libvirt.org/formatdomain.html#elementsRng
it is recommended to use `/dev/urandom` instead of `/dev/random` to avoid some of
limitation which `/dev/random` have. Also installer uses `/dev/urandom` in the
instance template.

- https://bugzilla.redhat.com/show_bug.cgi?id=1803130