Fix ejabberd API permission for akkounts VMs

It should have been using a /32, not a /8 subnet, in order to only allow
the akkounts VM(s) to use the API endpoints without further
authorization.

site-cookbooks/kosmos-ejabberd/templates/ejabberd.yml.erb

@@ -177,7 +177,7 @@ api_permissions:
   "akkounts":
     who:
 <% @akkounts_ip_addresses.each do |ip| -%>
-      - ip: "<%= ip %>/8"
+      - ip: "<%= ip %>/32"
 <% end -%>
     what:
       - "add_rosteritem"