Migrated to v4 of artifact

Author: SGI-CAPP-AT2

.github/workflows/flutterci.yml

@@ -44,7 +44,7 @@ jobs:
       - run: flutter build apk
 
       # Step 9: Upload the built APK as an artifact
-      - uses: actions/upload-artifact@v3
+      - uses: actions/upload-artifact@v4
         with:
           name: release-apk
           path: build/app/outputs/apk/release/app-release.apk