Add integration test and update dependencies

Introduced an integration test in app_test.dart for end-to-end testing. Updated pubspec.yaml to switch serious_python to the main branch and added integration_test and flet_integration_test to dev_dependencies.

{{cookiecutter.out_dir}}/integration_test/app_test.dart

@@ -0,0 +1,55 @@
+import 'package:flet_integration_test/flet_integration_test.dart';
+import 'package:flutter/foundation.dart';
+import 'package:flutter_test/flutter_test.dart';
+import 'package:integration_test/integration_test.dart';
+
+import 'package:{{ cookiecutter.project_name }}/main.dart' as app;
+
+void main() {
+  final binding = IntegrationTestWidgetsFlutterBinding.ensureInitialized();
+
+  group('end-to-end test', () {
+    testWidgets('test app', (tester) async {
+      const testerServerUrl = String.fromEnvironment('FLET_TEST_SERVER_URL');
+      late FlutterWidgetTester widgetTester;
+
+      if (testerServerUrl.isNotEmpty) {
+        debugPrint('Connecting to remote tester at $testerServerUrl');
+        widgetTester = await RemoteWidgetTester.connect(
+          tester: tester,
+          binding: binding,
+          serverUri: Uri.parse(testerServerUrl),
+        );
+      } else {
+        widgetTester = FlutterWidgetTester(tester, binding);
+      }
+
+      app.tester = widgetTester;
+
+      final args = <String>[];
+
+      const fletTestAppUrl = String.fromEnvironment('FLET_TEST_APP_URL');
+      if (fletTestAppUrl.isNotEmpty) {
+        args.add(fletTestAppUrl);
+      }
+
+      const fletTestPidFile = String.fromEnvironment('FLET_TEST_PID_FILE_PATH');
+      if (fletTestPidFile.isNotEmpty) {
+        args.add(fletTestPidFile);
+      }
+
+      const fletTestAssetsDir = String.fromEnvironment('FLET_TEST_ASSETS_DIR');
+      if (fletTestAssetsDir.isNotEmpty) {
+        args.add(fletTestAssetsDir);
+      }
+
+      app.main(args);
+
+      await Future<void>.delayed(const Duration(milliseconds: 500));
+      await widgetTester.pump(duration: const Duration(seconds: 1));
+      await widgetTester
+          .pumpAndSettle(duration: const Duration(milliseconds: 100));
+      await widgetTester.waitForTeardown();
+    });
+  });
+}

{{cookiecutter.out_dir}}/pubspec.yaml

@@ -32,7 +32,7 @@ dependency_overrides:
   serious_python:
     git:
       url: https://github.com/flet-dev/serious-python.git
-      ref: android-16k
+      ref: main
       path: src/serious_python
 
   wakelock_plus: ^1.2.10
@@ -56,6 +56,13 @@ dev_dependencies:
   flutter_launcher_icons: ^0.14.1
   flutter_native_splash: ^2.4.1
   flutter_lints: ^2.0.0
+  integration_test:
+    sdk: flutter
+  flet_integration_test:
+    git:
+      url: https://github.com/flet-dev/flet.git
+      ref: v1-flet-test
+      path: packages/flet_integration_test
 
 flutter: