fix : createDate,modifyDate 자동 적용되도록 설정

Author: taekkong

src/main/java/org/tuna/zoopzoop/backend/BackendApplication.java

@@ -2,8 +2,10 @@
 
 import org.springframework.boot.SpringApplication;
 import org.springframework.boot.autoconfigure.SpringBootApplication;
+import org.springframework.data.jpa.repository.config.EnableJpaAuditing;
 
 @SpringBootApplication
+@EnableJpaAuditing
 public class BackendApplication {
     public static void main(String[] args) {
         SpringApplication.run(BackendApplication.class, args);