Update build.yaml

Author: cloudwebrtc

.github/workflows/build.yaml

@@ -77,6 +77,8 @@ jobs:
           channel: 'stable'
       - name: Install project dependencies
         run: flutter pub get
+      - name: Install xcode platform support for iOS
+        run: xcodebuild -downloadPlatform iOS
       - name: Build for iOS
         working-directory: ./example
         run: flutter build ios --release --no-codesign
@@ -170,4 +172,4 @@ jobs:
         run: flutter pub get
       - name: Build for Web
         working-directory: ./example
-        run: flutter build web --wasm
+        run: flutter build web --wasm