fix: 세션 저장을 위한 직렬화 요소 추가

Author: Gooraeng

back/src/main/java/com/back/domain/user/entity/User.java

@@ -10,6 +10,7 @@
 import lombok.*;
 import org.springframework.data.annotation.LastModifiedDate;
 
+import java.io.Serializable;
 import java.time.LocalDateTime;
 import java.util.ArrayList;
 import java.util.List;
@@ -25,7 +26,7 @@
 @NoArgsConstructor
 @AllArgsConstructor
 @Builder
-public class User extends BaseEntity {
+public class User extends BaseEntity implements Serializable {
 
     @Column(nullable = false, unique = true)
     private String email;