Add Node.js setup

Author: frankieroberto

.github/workflows/tests.yml

@@ -9,6 +9,11 @@ jobs:
     steps:
       - name: Checkout
         uses: actions/checkout@v4
+      - name: Setup Node.js
+        uses: actions/setup-node@v4
+        with:
+          node-version: 20
+          cache: 'npm'
       - name: Install dependencies
         run: npm ci
       - name: Build with Eleventy