ci: build Maven in GitHub Actions

.github/workflows/main.yml

@@ -0,0 +1,18 @@
+name: Continuous Integration
+
+on:
+  push:
+    branches: [main]
+  pull_request:
+    branches: [main]
+
+jobs:
+  build_and_test:
+    runs-on: ubuntu-latest
+
+    steps:
+      - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
+      - uses: actions/setup-java@8df1039502a15bceb9433410b1a100fbe190c53b # v4.5.0
+        with:
+          java-version: 14
+      - run: mvn -B package --file pom.xml