Fixed github actions recommendations and removed redundant files

.github/workflows/check_pr.yml

@@ -27,14 +27,8 @@ jobs:
           channel: 'stable'
       - run: flutter --version
 
-      # Note: This workflow uses the latest stable version of the Dart SDK.
-      # You can specify other versions if desired, see documentation here:
-      # https://github.com/dart-lang/setup-dart/blob/main/README.md
-      # - uses: dart-lang/setup-dart@v1
-      - uses: dart-lang/setup-dart@9a04e6d73cca37bd455e0608d7e5092f881fd603
-
       - name: Install dependencies
-        run: dart pub get
+        run: flutter pub get
 
       # Uncomment this step to verify the use of 'dart format' on each commit.
       # - name: Verify formatting

example/integration_test/plugin_integration_test.dart

@@ -16,9 +16,9 @@ void main() {
 
   testWidgets('getPlatformVersion test', (WidgetTester tester) async {
     final AdyenCheckout plugin = AdyenCheckout();
-    final String? version = await plugin.getPlatformVersion();
+    final String version = await plugin.getPlatformVersion();
     // The version string depends on the host platform running the test, so
     // just assert that some non-empty string is returned.
-    expect(version?.isNotEmpty, true);
+    expect(version.isNotEmpty, true);
   });
 }

example/lib/main.dart

@@ -41,8 +41,7 @@ class _MyAppState extends State<MyApp> {
     // Platform messages may fail, so we use a try/catch PlatformException.
     // We also handle the message potentially returning null.
     try {
-      platformVersion = await _adyenCheckout.getPlatformVersion() ??
-          'Unknown platform version';
+      platformVersion = await _adyenCheckout.getPlatformVersion();
     } on PlatformException {
       platformVersion = 'Failed to get platform version.';
     }