Update build.yml to include the build_runner phase

Needed for the new test that uses a mock client

.github/workflows/build.yml

@@ -52,7 +52,6 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        # The example Android project setup ist not supported by Flutter 3.10.x
         sdk: [ min, stable, beta ]
     steps:
       - uses: actions/checkout@v4
@@ -66,6 +65,8 @@ jobs:
           cache: true
           flutter-version: ${{ matrix.sdk == 'min' && env.FLUTTER_MIN_SDK || '' }}
           channel: ${{ matrix.sdk == 'min' && 'stable' || matrix.sdk }}
+      - run: flutter pub get
+      - run: dart run build_runner build --delete-conflicting-outputs
       - name: Build example APK
         working-directory: example
         run: flutter build apk
@@ -93,6 +94,8 @@ jobs:
       - uses: maxim-lobanov/setup-cocoapods@v1
         with:
           version: latest
+      - run: flutter pub get
+      - run: dart run build_runner build --delete-conflicting-outputs
       - name: Build example iOS package
         run: flutter build ios --simulator
         working-directory: example
@@ -123,6 +126,8 @@ jobs:
           sudo apt-get install -y ninja-build
           sudo apt-get install -y libgtk-3-dev
           export CMAKE_CXX_COMPILER=$(which g++)
+      - run: flutter pub get
+      - run: dart run build_runner build --delete-conflicting-outputs
       - name: Build example Linux package
         run: flutter build linux
         working-directory: example
@@ -131,4 +136,4 @@ jobs:
         uses: actions/upload-artifact@v4
         with:
           name: background-downloader-demo-linux
-          path: example/build/linux/x64/release/bundle
+          path: example/build/linux/x64/release/bundle