npm-publish: use Node.js 20

Author: XhmikosR

.github/workflows/npm-publish.yml

@@ -19,7 +19,7 @@ jobs:
       - name: Use Node.js
         uses: actions/setup-node@v4
         with:
-          node-version: 18
+          node-version: 20
           cache: npm
       - run: npm ci
       - id: publish