Samples maintenance (#435)

provider_shopper/test/cart_widget_test.dart

@@ -47,7 +47,7 @@ void main() {
       await tester.pumpWidget(createCartScreen());
 
       // Adding five items in the cart and testing.
-      for (int i = 0; i < 5; i++) {
+      for (var i = 0; i < 5; i++) {
         var item = catalogModel.getByPosition(i);
         cartModel.add(item);
         await tester.pumpAndSettle();