[libgdx] Update GitHub Action to use Gradle

.github/workflows/spine-libgdx.yml

@@ -12,24 +12,18 @@ jobs:
     steps:
     - uses: actions/checkout@v3
     - name: Set up JDK 1.8
-      uses: actions/setup-java@v3 
+      uses: actions/setup-java@v3
       with:
         distribution: 'zulu'
-        java-version: "8"       
-        server-id: sonatype-nexus-snapshots
-        server-username: MAVEN_USERNAME
-        server-password: MAVEN_PASSWORD
+        java-version: "8"
 
-    - name: Cache Maven packages
+    - name: Cache Gradle packages
       uses: actions/cache@v3
       with:
-        path: ~/.m2
-        key: ${{ runner.os }}-m2-${{ hashFiles('**/pom.xml') }}
-        restore-keys: ${{ runner.os }}-m2
+        path: ~/.gradle/caches
+        key: ${{ runner.os }}-gradle-${{ hashFiles('**/*.gradle*') }}
+        restore-keys: ${{ runner.os }}-gradle
 
     - name: Build spine-libgdx
-      working-directory: spine-libgdx/spine-libgdx      
-      run: mvn clean deploy
-      env:
-          MAVEN_USERNAME: ${{ secrets.SONATYPE_USER }}
-          MAVEN_PASSWORD: ${{ secrets.SONATYPE_PASSWORD }}
+      working-directory: spine-libgdx/spine-libgdx
+      run: ./gradlew publishReleasePublicationToSonaType -PossrhUsername=${{ secrets.SONATYPE_USER }} -PossrhPassword=${{ secrets.SONATYPE_PASSWORD }}