chore: update Node.js version to 20 in sync-docs.yml

Author: ReneWerner87

.github/workflows/sync-docs.yml

@@ -26,7 +26,7 @@ jobs:
             - name: Setup Node.js environment
               uses: actions/setup-node@v6
               with:
-                  node-version: '18'
+                  node-version: '20'
 
             - name: Sync docs
               run: ./.github/scripts/sync_docs.sh