Update GitHub Actions workflow for Gradle setup

.github/workflows/build.yml

@@ -20,11 +20,13 @@ jobs:
           distribution: temurin
           java-version: 17
 
-      - name: Grant execute permission for Gradle
-        run: chmod +x gradlew
+      - name: Set up Gradle
+        uses: gradle/gradle-build-action@v2
+        with:
+          gradle-version: 9.6  # or whatever version your mod uses
 
       - name: Build mod
-        run: ./gradlew build
+        run: gradle build
 
       - name: Read mod name and version
         id: mod_info