feat: upgrade to bobcat (#887)

diff --git a/images/magnum/Earthfile b/images/magnum/Earthfile
index f7e189f..645d99c 100644
--- a/images/magnum/Earthfile
+++ b/images/magnum/Earthfile
@@ -1,18 +1,21 @@
 VERSION 0.7
 
+ARG --global PROJECT=magnum
+ARG --global RELEASE=2023.2
+ARG --global PROJECT_REF=156f6f52d38a670e6fe10725966aeea4ddf65146
+
+build:
+  FROM ../openstack-service+builder --RELEASE=${RELEASE}
+  DO ../openstack-service+BUILD_VENV \
+    --PROJECT=${PROJECT} \
+    --PROJECT_REF=${PROJECT_REF} \
+    --PIP_PACKAGES="magnum-cluster-api==0.13.3"
+
 image:
-  ARG PROJECT=magnum
-  ARG RELEASE=zed
-  ARG REF=c671d8baf9d6f4705a1b832ae2d96980e5a58db6
-  FROM ../openstack-service+image \
-    --PROJECT ${PROJECT} \
-    --RELEASE ${RELEASE} \
-    --PROJECT_REF ${REF} \
-    --PIP_PACKAGES "magnum-cluster-api==0.13.3"
-  DO \
-    ../+APT_INSTALL \
+  FROM ../openstack-service+image --RELEASE ${RELEASE} --PROJECT ${PROJECT}
+  COPY +build/venv /var/lib/openstack
+  DO ../+APT_INSTALL \
     --PACKAGES "haproxy"
-  DO ../+APPLY_PATCHES
   SAVE IMAGE --push \
     ghcr.io/vexxhost/atmosphere/${PROJECT}:${RELEASE} \
-    ghcr.io/vexxhost/atmosphere/${PROJECT}:${REF}
+    ghcr.io/vexxhost/atmosphere/${PROJECT}:${PROJECT_REF}