Fix missing closing tag for identity node in presence stanza

resources/prosody-plugins/util.lib.lua

         if creator_group then
             stanza:tag("creator_group"):text(creator_group):up();
         end
-        stanza:up();
     end
 
+    stanza:up(); -- Close identity tag
 end
 
 -- Utility function to check whether feature is present and enabled. Allow