remove obsolete widget test

-// This is a basic Flutter widget test.
-//
-// To perform an interaction with a widget in your test, use the WidgetTester
-// utility that Flutter provides. For example, you can send tap and scroll
-// gestures. You can also use WidgetTester to find child widgets in the widget
-// tree, read text, and verify that the values of widget properties are correct.
-
-import 'package:flutter_test/flutter_test.dart';
-
-void main() {
-  testWidgets('Verify Platform version', (WidgetTester tester) async {
-    // Build our app and trigger a frame.
-  });
-}