Fix workflow: Update Node.js version to 20 for vsce compatibility

.github/workflows/publish.yml

@@ -16,7 +16,7 @@ jobs:
     - name: Setup Node.js
       uses: actions/setup-node@v4
       with:
-        node-version: '18'
+        node-version: '20'
         cache: 'npm'
         
     - name: Install dependencies