Add platform option to Dioxus build command

Author: skutcher

.github/workflows/deploy.yml

@@ -26,7 +26,7 @@ jobs:
 
       - name: Build Dioxus Web App (in frontend/)
         working-directory: frontend
-        run: dx build
+        run: dx build --platform web
 
       - name: Upload GitHub Pages artifact
         uses: actions/upload-pages-artifact@v3