add publish workflow

.github/workflows/publish.yml

@@ -0,0 +1,23 @@
+name: npm-publish
+
+# run when a tag is pushed or kick off manually
+on:
+  push:
+    tags:
+      - '*'
+  workflow_dispatch:
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+
+    steps:
+      - uses: actions/checkout@v2
+      - uses: actions/setup-node@v1
+        with:
+          node-version: '12.x'
+          registry-url: 'https://registry.npmjs.org'
+      - run: npm install
+      - run: npm publish --access public
+        env:
+          NODE_AUTH_TOKEN: ${{ secrets.NPM_TOKEN }}