[mob][photos] Update people section after clustering

mobile/lib/services/machine_learning/face_ml/face_ml_service.dart

@@ -493,6 +493,7 @@ class FaceMlService {
         _logger.info('Done updating FaceIDs with clusterIDs in the DB, in '
             '${DateTime.now().difference(clusterDoneTime).inSeconds} seconds');
       }
+      Bus.instance.fire(PeopleChangedEvent());
       _logger.info('clusterAllImages() finished, in '
           '${DateTime.now().difference(clusterAllImagesTime).inSeconds} seconds');
       isClusteringRunning = false;