Update acm to v2.12

Tested on hub+spoke and everything worked correctly.

Author: mbaldessari

values-hub.yaml

@@ -11,8 +11,7 @@ clusterGroup:
     acm:
       name: advanced-cluster-management
       namespace: open-cluster-management
-      channel: release-2.11
-      #csv: advanced-cluster-management.v2.6.1
+      channel: release-2.12
   projects:
     - hub
     - config-demo