Add pull request workflow for GitHub Actions

.github/workflows/pull-request.yml

@@ -0,0 +1,25 @@
+name: Pull request workflow
+on: pull_request
+
+permissions:
+  contents: write
+  pull-requests: write
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v3
+      - name: Setup Gradle
+        uses: gradle/gradle-build-action@v2
+      - name: Run checks with Gradle Wrapper
+        run: ./gradlew check
+  automerge:
+    runs-on: ubuntu-latest
+    if: ${{ github.actor == 'wbrawner' }}
+    steps:
+      - name: Enable auto-merge
+        run: gh pr merge --auto --merge "$PR_URL"
+        env:
+          PR_URL: ${{github.event.pull_request.html_url}}
+          GITHUB_TOKEN: ${{secrets.GITHUB_TOKEN}}