Add CI

.github/workflows/gradle.yml

@@ -0,0 +1,26 @@
+name: build
+
+on:
+  push:
+    branches: [ master ]
+  pull_request:
+    branches: [ master ]
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        java: [ '17', '21' ]
+    name: Build
+    steps:
+    - uses: actions/checkout@v4
+    - name: Set up JDK ${{ matrix.java }}
+      uses: actions/setup-java@v4
+      with:
+        java-version: ${{ matrix.java }}
+        distribution: 'temurin'
+    - name: Run tests
+      uses: gradle/actions/setup-gradle@v3
+      with:
+        arguments: test