chore: Add minimal CI setup accommodating PRs on GitHub.

Signed-off-by: Michael Simons <michael.simons@neo4j.com>

Author: michael-simons

.github/workflows/build.yml

@@ -0,0 +1,40 @@
+name: build
+
+on:
+  push:
+    branches:
+      - master
+    paths-ignore:
+      - 'README.md'
+      - 'CONTRIBUTING.adoc'
+  pull_request:
+    paths-ignore:
+      - 'README.md'
+      - 'CONTRIBUTING.adoc'
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+      - name: 'Set up JDK'
+        uses: actions/setup-java@v4
+        with:
+          distribution: zulu
+          java-version: 8
+
+      - name: 'Cache Gradle packages'
+        uses: actions/cache@v4
+        with:
+          path: |
+            ~/.gradle/caches
+            ~/.gradle/wrapper
+          key: ${{ runner.os }}-gradle-${{ hashFiles('**/*.gradle*', '**/gradle-wrapper.properties') }}
+          restore-keys: |
+            ${{ runner.os }}-gradle-
+
+      - name: 'Checkout'
+        uses: actions/checkout@v4
+
+      - name: 'Build and test'
+        run: |
+          ./gradlew build