Use node 16 in CI to avoid cypress timeout issue.

.github/workflows/ci.yml

@@ -18,10 +18,10 @@ jobs:
       - uses: actions/checkout@v2
         with:
           submodules: recursive
-      - name: Use Node.js 18
+      - name: Use Node.js 16
         uses: actions/setup-node@v1
         with:
-          node-version: 18
+          node-version: 16
       # Re-use node_modules between runs until package-lock.json changes.
       - name: Cache node_modules
         id: cache-node_modules