Try Node 20.2 to fix esbuild error in CI.

.github/workflows/ci.yml

@@ -21,7 +21,7 @@ jobs:
       - name: Use Node.js 20
         uses: actions/setup-node@v1
         with:
-          node-version: 20
+          node-version: 20.2
       # Re-use node_modules between runs until package-lock.json changes.
       - name: Cache node_modules
         id: cache-node_modules