bool isstale:Add bool isstale to store.dart

Author: satyam372

pubspec.yaml

@@ -40,7 +40,6 @@ dependencies:
     sdk: flutter
 
   app_settings: ^5.0.0
-
   collection: ^1.17.2
   convert: ^3.1.1
   crypto: ^3.0.3
@@ -145,4 +144,4 @@ flutter:
       fonts:
         - asset: assets/icons/ZulipIcons.ttf
 
-    # If adding a font, remember to account for its license in lib/licenses.dart.
+    # If adding a font, remember to account for its license in lib/licenses.dart.