fix: set up Java for backend in .yml file

.github/workflows/main.yml

@@ -12,10 +12,10 @@ jobs:
 
     steps:
       - name: Checkout code
-        uses: actions/checkout@v2
+        uses: actions/checkout@v4
 
       - name: Set up Node.js for Frontend
-        uses: actions/setup-node@v2
+        uses: actions/setup-node@v4
         with:
           node-version: '20.17.0'
 
@@ -30,20 +30,23 @@ jobs:
           npm run build
 
       - name: Set up Java for Backend
-        uses: actions/setup-java@v2
+        uses: actions/setup-java@v4
         with:
-          distribution: 'oracle'
-          java-version: '22.0.2'
+          distribution: 'temurin'
+          java-version: '22'
+          cache: 'maven'
+          cache-dependency-path: 'backend/pom.xml'
 
-      - name: Build Backend
+      - name: Build Backend with Maven
         run: |
           cd backend
-          mvnw package
+          mvn -B package --file pom.xml
 
   deploy:
+    needs: build
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v4
       - uses: akhileshns/[email protected]
         with:
           heroku_api_key: ${{secrets.HEROKU_API_KEY}}
@@ -56,4 +59,4 @@ jobs:
           heroku_api_key: ${{secrets.HEROKU_API_KEY}}
           heroku_app_name: ${{secrets.HEROKU_BACKEND_APP_NAME}}
           heroku_email: ${{secrets.HEROKU_EMAIL}}
-          appdir: "backend"
+          appdir: "backend"