Add gradle build GitHub Action

.github/workflows/build.yml

@@ -0,0 +1,22 @@
+name: Run Gradle Build
+on: [push, pull_request]
+jobs:
+  gradle:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout source
+        uses: actions/checkout@v3
+      - uses: actions/setup-java@v3
+        name: Setup Java
+        with:
+          distribution: temurin
+          java-version: 17
+      - name: Setup Gradle
+        uses: gradle/gradle-build-action@v2
+      - name: Execute Gradle build
+        run: ./gradlew build
+      - uses: actions/upload-artifact@v3
+        name: Upload built mod JAR
+        with:
+          name: mod-jar
+          path: build/libs/*.jar