Fix: BaseEntity 오타 수정 (#33)

Author: jueunk617

src/main/java/com/back/global/entity/BaseEntity.java

@@ -16,7 +16,7 @@ public abstract class BaseEntity {
     private Long id;
 
     @CreatedDate
-    private LocalDateTime createAt;
+    private LocalDateTime createdAt;
 
     @LastModifiedDate
     private LocalDateTime updatedAt;