Fix #27816: Outliner does not update when parents are cleared

Added NC_OBJECT|ND_PARENT notifier to OBJECT_OT_parent_clear operator.

source/blender/editors/object/object_relations.c

@@ -446,6 +446,7 @@ static int parent_clear_exec(bContext *C, wmOperator *op)
 	DAG_scene_sort(bmain, scene);
 	DAG_ids_flush_update(bmain, 0);
 	WM_event_add_notifier(C, NC_OBJECT|ND_TRANSFORM, NULL);
+	WM_event_add_notifier(C, NC_OBJECT|ND_PARENT, NULL);
 
 	return OPERATOR_FINISHED;
 }