Add a simple CI pipeline (now that it is free for public repo)

.github/workflows/test.yml

@@ -0,0 +1,20 @@
+name: Build
+
+on:
+  push:
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+    - name: Checkout sources
+      uses: actions/checkout@v4
+    - name: Setup Java
+      uses: actions/setup-java@v4
+      with:
+        distribution: 'temurin'
+        java-version: 17
+    - name: Setup Gradle
+      uses: gradle/actions/setup-gradle@v3
+    - name: Build with Gradle
+      run: ./gradlew build