build: reconfigure GitHub Actions for semantic release

.github/workflows/ci.yml

@@ -1,6 +1,6 @@
 name: Node.js CI
 
-on: [push, pull_request]
+on: [pull_request]
 
 jobs:
   build:

.github/workflows/release.yml

@@ -0,0 +1,26 @@
+name: Release
+on:
+  push:
+    branches:
+      - master
+jobs:
+  release:
+    name: Release
+    runs-on: ubuntu-18.04
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v1
+      - name: Setup Node.js
+        uses: actions/setup-node@v1
+        with:
+          node-version: 12
+      - name: Install dependencies
+        run: npm ci
+      - name: Lint
+        run: npm run lint
+      - name: Test
+        run: npm test
+      - name: Release
+        env:
+          NPM_TOKEN: ${{ secrets.NPM_TOKEN }}
+        run: npx semantic-release