bump gitlab ci node to version 20.x

.gitea/workflows/default.yml

@@ -13,10 +13,10 @@ jobs:
     runs-on: ubuntu-latest
     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
           cache: 'npm'
       - run: npm install
       - run: npm run build