[FIX]도커 빌드 에러 수정

.github/workflows/gradle.yml

@@ -54,7 +54,7 @@ jobs:
       run: |
           docker login -u ${{ secrets.DOCKER_USERNAME }} -p ${{ secrets.DOCKER_PASSWORD }}
           docker build -t ${{ secrets.DOCKER_USERNAME }}/${{ secrets.DOCKER_REPO }} .
-          docker push ${{ secrets.DOCKER_USERNAME }}/${{ secrets.DOCKER_REPO }}
+          docker push ${{ secrets.DOCKER_USERNAME }}/${{ secrets.DOCKER_REPO }}:latest
  
       # EC2에 접속하고 배포합니다.
     - name: Deploy