Fix: Build demo by changing directory instead of using workspace

Author: Ibrahim

.github/workflows/deploy-demo.yml

@@ -39,7 +39,9 @@ jobs:
         run: npm run build --workspace=wex-threejs
 
       - name: Build demo
-        run: npm run build --workspace=@xbim/wex-threejs-demo
+        run: |
+          cd packages/demo
+          npm run build
         env:
           NODE_ENV: production