Update windows CI workflow to build frontend for testing

Author: chengr4

.github/workflows/ci.yml

@@ -81,6 +81,10 @@ jobs:
   test_on_windows:
     name: Test on Windows
     runs-on: windows-latest
+    strategy:
+      matrix:
+        node-version: [20.x]
+
     steps:
       - name: Checkout the source code
         uses: actions/checkout@v2
@@ -102,6 +106,17 @@ jobs:
         env:
             RUSTFLAGS: -Dwarnings
 
+      - name: Use Node.js ${{ matrix.node-version }}
+        uses: actions/setup-node@v3
+        with:
+          node-version: ${{ matrix.node-version }}
+
+      - name: Build frontend for testing
+        run: |
+          npm ci
+          npm run build
+        working-directory: ./site/frontend
+
       - name: Run unit tests
         run: cargo test --all