ceph-mon: bump charmcraft version to 2.x

This is necessary as older charmcraft doesn't support dependency
resolution via the PYDEPS mechanism, which is required by the
grafana agent library

charmed_openstack_info/data/lp-builder-config/ceph.yaml

@@ -288,7 +288,7 @@ projects:
       stable/quincy.2:
         series-summary: "Quincy stable charm"
         build-channels:
-          charmcraft: "2.0/stable"
+          charmcraft: "2.x/stable"
         channels:
           - quincy/stable
         bases: