Add GitHub Action for publishing to npm

.github/workflows/publish.yml

@@ -0,0 +1,28 @@
+name: Publish to npm
+
+on:
+  push:
+    branches:
+      - main
+
+jobs:
+  publish:
+    runs-on: ubuntu-latest
+
+    steps:
+    - name: Checkout repository
+      uses: actions/checkout@v2
+
+    - name: Setup Node.js
+      uses: actions/setup-node@v2
+      with:
+        node-version: '14'
+        registry-url: 'https://registry.npmjs.org/'
+
+    - name: Install dependencies
+      run: npm install
+
+    - name: Publish to npm
+      run: npm publish
+      env:
+        NODE_AUTH_TOKEN: ${{ secrets.NPM_TOKEN }}