nudge user to clean trash after de-duplication

lib/ui/settings/backup_section_widget.dart

@@ -254,7 +254,7 @@ class BackupSectionWidgetState extends State<BackupSectionWidget> {
             ),
           ),
           onPressed: () {
-            // TODO: After trash implementation - showToast("also empty your \"Trash\" to claim the freed up space");
+            showToast("also empty your \"Trash\" to claim the freed up space");
             Navigator.of(context, rootNavigator: true).pop('dialog');
           },
         ),