[refac] fix HankkiResponse.java as api spec

src/main/java/org/hankki/hankkiserver/api/dto/HankkiResponse.java

@@ -11,7 +11,7 @@
 @RequiredArgsConstructor(access = AccessLevel.PRIVATE)
 public class HankkiResponse<T> {
 
-    private final int status;
+    private final int code;
     private final String message;
     @JsonInclude(value = JsonInclude.Include.NON_NULL)
     private T data;