add github workflow

.github/workflows/gradle.yml

@@ -0,0 +1,26 @@
+# Adapted from Paper's build script
+name: Build
+on: [ push, pull_request ]
+
+jobs:
+  build:
+    # Only run on PRs if the source branch is on someone else's repo
+    if: ${{ github.event_name != 'pull_request' || github.repository != github.event.pull_request.head.repo.full_name }}
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        java: [ 17 ]
+      fail-fast: true
+    steps:
+      - uses: actions/checkout@v3
+      - name: JDK ${{ matrix.java }}
+        uses: actions/setup-java@v3
+        with:
+          java-version: ${{ matrix.java }}
+          cache: 'gradle'
+          distribution: 'temurin'
+      - name: Build
+        run: |
+          git config --global user.email "no-reply@github.com"
+          git config --global user.name "Github Actions"
+          ./gradlew build --stacktrace