ci: let publish workflow use node v20 like in test workflow

Author: consideRatio

.github/workflows/publish.yaml

@@ -41,7 +41,7 @@ jobs:
       - uses: actions/setup-node@v3
         with:
           cache: yarn
-          node-version: 18.x
+          node-version: 20.x
           registry-url: https://registry.npmjs.org
           cache-dependency-path: labextension/yarn.lock