Update ci.yml to use node20

.github/workflows/ci.yml

@@ -12,10 +12,10 @@ jobs:
 
     steps:
       - uses: actions/checkout@v3
-      - name: Use Node.js 18.x
+      - name: Use Node.js 20.x
         uses: actions/setup-node@v3
         with:
-          node-version: 18.x
+          node-version: 20.x
       - run: npm ci
       - run: npm test
       - name: codecov