fix: yml 수정

.github/workflows/back.yml

@@ -17,7 +17,19 @@ jobs:
         uses: actions/checkout@v4
 
       - name: Set up Docker
-        uses: docker/setup-buildx-action@v3
+        uses: decker/setup-buildx-action@v3
+
+      - name: Set up JDK 21
+        uses: actions/setup-java@v4
+        with:
+          distribution: 'temurin'
+          java-version: '21'
+
+      - name: Set up Gradle
+        uses: gradle/gradle-build-action@v3
+
+      - name: Build with Gradle
+        run: ./gradlew build
 
       - name: Login to ghcr
         uses: docker/login-action@v3
@@ -30,6 +42,7 @@ jobs:
         uses: docker/build-push-action@v5
         with:
           context: .
+          file: ./Dockerfile
           push: true
           tags: ghcr.io/yunuo46/getaguitar:latest