build: switch to release-please action (bcoe#260)

.github/workflows/ci.yaml

@@ -3,6 +3,7 @@ on:
     branches:
       - master
   pull_request:
+    types: [ assigned, opened, synchronize, reopened, labeled ]
 name: ci
 jobs:
   test:

.github/workflows/release-please.yml

@@ -0,0 +1,31 @@
+on:
+  push:
+    branches:
+      - master
+name: release-please
+jobs:
+  release-please:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: GoogleCloudPlatform/release-please-action@v2.4.2
+        id: release
+        with:
+          token: ${{ secrets.GITHUB_TOKEN }}
+          release-type: node
+          package-name: c8
+      # The logic below handles the npm publication:
+      - uses: actions/checkout@v2
+        # these if statements ensure that a publication only occurs when
+        # a new release is created:
+        if: ${{ steps.release.outputs.release_created }}
+      - uses: actions/setup-node@v1
+        with:
+          node-version: 12
+          registry-url: 'https://external-dot-oss-automation.appspot.com'
+        if: ${{ steps.release.outputs.release_created }}
+      - run: npm ci
+        if: ${{ steps.release.outputs.release_created }}
+      - run: npm publish
+        env:
+          NODE_AUTH_TOKEN: ${{secrets.NPM_TOKEN}}
+        if: ${{ steps.release.outputs.release_created }}