run npm publish on actions.

.github/workflows/publish.yml

@@ -0,0 +1,27 @@
+name: publish
+on:
+  release:
+    types: [published]
+
+jobs:
+  unit-tests-and-publish:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+      - name: setup node
+        uses: actions/setup-node@v2
+        with:
+          node-version: '14'
+          registry-url: 'https://registry.npmjs.org'
+      - name: setup deno
+        uses: denoland/setup-deno@v1
+        with:
+          deno-version: v1.x
+      - name: install dependencies
+        run: npm ci
+      - name: tests
+        run: npm run test
+      - name: publish
+        run: npm publish
+        env:
+          NODE_AUTH_TOKEN: ${{ secrets.NPM_TOKEN }}