Update npm publish workflow for Node 20

https://github.blog/changelog/2024-03-07-github-actions-all-actions-will-run-on-node20-instead-of-node16-by-default/

.github/workflows/npm-publish.yml

@@ -7,10 +7,10 @@ jobs:
  build:
    runs-on: ubuntu-latest
    steps:
-     - uses: actions/checkout@v3
-     - uses: actions/setup-node@v3
+     - uses: actions/checkout@v4
+     - uses: actions/setup-node@v4
        with:
-         node-version: '18.x'
+         node-version: '20.x'
          registry-url: 'https://registry.npmjs.org'
      - run: npm install -g npm
      - run: npm publish --access public