Permit Juju 3.1

Allow juju 3.1 as CMR fixes should have been backported and 3.1 has a longer
life than 3.2

Change-Id: I7f136c163eb763330c7ff4ef5e914321f7fe2fcf

.zuul.yaml

@@ -2,10 +2,17 @@
     templates:
       - openstack-python3-charm-yoga-jobs
       - openstack-cover-jobs
-      - microk8s-func-test
+#      - microk8s-func-test
+    check:
+      jobs:
+        - charmbuild:
+            nodeset: ubuntu-focal
+        - zaza-smoke-test:
+            nodeset: ubuntu-focal
+            voting: false
     vars:
       charm_build_name: ovn-central-k8s
-      juju_channel: 3.2/stable
+      juju_channel: 3.1/stable
       juju_classic_mode: false
       microk8s_channel: 1.26-strict/stable
       microk8s_classic_mode: false

metadata.yaml

@@ -30,7 +30,7 @@ bases:
     channel: 22.04/stable
 assumes:
   - k8s-api
-  - juju >= 3.2
+  - juju >= 3.1
 storage:
   databases:
     type: filesystem