Update versions in publishing CI workflow (#18)

.github/workflows/npm-publish.yml

@@ -9,21 +9,21 @@ jobs:
   build:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v2
-      - uses: actions/setup-node@v1
+      - uses: actions/checkout@v4
+      - uses: actions/setup-node@v3.8.1
         with:
-          node-version: 18
+          node-version: 20
       - run: npm install
       - run: npm run test
 
   publish-npm:
     needs: build
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v2
-      - uses: actions/setup-node@v1
+      - uses: actions/checkout@v4
+      - uses: actions/setup-node@v3.8.1
         with:
-          node-version: 18
+          node-version: 20
           registry-url: https://registry.npmjs.org/
       - run: npm install
       - run: npm publish --access public