Update Node.js version from 20 to 22

Author: otoneko1102

.github/workflows/docs.yml

@@ -26,7 +26,7 @@ jobs:
       - name: Setup Node.js
         uses: actions/setup-node@v4
         with:
-          node-version: "20"
+          node-version: "22"
 
       - name: Install dependencies
         run: cd pages && npm install