publish-to-charmhub: Pin charmcraft to specific older version 2.2/stable

Change-Id: I379ad38fe753c3807208341a053de2b1f510a5cf
diff --git a/playbooks/charm-cinder-storpool-iscsi/publish-to-charmhub.yaml b/playbooks/charm-cinder-storpool-iscsi/publish-to-charmhub.yaml
index b1cd1fe..2ced64e 100644
--- a/playbooks/charm-cinder-storpool-iscsi/publish-to-charmhub.yaml
+++ b/playbooks/charm-cinder-storpool-iscsi/publish-to-charmhub.yaml
@@ -4,7 +4,7 @@
   tasks:
 
     - name: Install charmcraft
-      ansible.builtin.command: snap install charmcraft --classic
+      ansible.builtin.command: snap install charmcraft --classic --channel=2.2/stable
       become: true
 
     - name: Initialize lxd