[stable/zed] Refactor image tags to be dynamic (#1122)

In order to simplify backporting and branching of new releases,
this patch relies on the Zuul branch when building images so
that we can easily branch out a new release and it will
automatically pick up the images.
Closes: #1121
diff --git a/images/libvirtd/Dockerfile b/images/libvirtd/Dockerfile
index 51cad16..65ae2d2 100644
--- a/images/libvirtd/Dockerfile
+++ b/images/libvirtd/Dockerfile
@@ -12,7 +12,9 @@
 # License for the specific language governing permissions and limitations
 # under the License.
 
-FROM registry.atmosphere.dev/library/openstack-runtime:zed
+ARG RELEASE
+
+FROM registry.atmosphere.dev/library/openstack-runtime:${RELEASE}
 ADD --chmod=644 https://download.ceph.com/keys/release.gpg /etc/apt/trusted.gpg.d/ceph.gpg
 COPY <<EOF /etc/apt/sources.list.d/ceph.list
 deb http://download.ceph.com/debian-reef/ jammy main