Fix T83497: missing relations update when group node changes

Changing which node group a group node references needs a depsgraph
relations update in some cases.

Differential Revision: https://developer.blender.org/D10018

source/blender/makesrna/intern/rna_nodetree.c

@@ -3245,6 +3245,7 @@ static void rna_NodeGroup_update(Main *bmain, Scene *UNUSED(scene), PointerRNA *
   }
 
   ED_node_tag_update_nodetree(bmain, ntree, node);
+  DEG_relations_tag_update(bmain);
 }
 
 static void rna_NodeGroup_node_tree_set(PointerRNA *ptr,