ci(dart): add example test flow

add example test flow

Author: simeng-li

.github/workflows/example.yml

@@ -32,5 +32,22 @@ jobs:
       - name: Test
         run: flutter test --no-pub --coverage
 
-      - name: Example Test
-        run: cd example && flutter test --no-pub
+  example:
+    runs-on: ubuntu-latest
+
+    steps:
+      - uses: actions/checkout@v3
+
+      - name: Setup Flutter
+        uses: subosito/flutter-action@v2
+        with:
+          channel: stable
+
+      - name: Install
+        run: flutter pub get
+
+      - name: Analyze
+        run: cd example && flutter analyze --no-pub
+
+      - name: Test
+        run: cd example && flutter test --no-pub --coverage