text: Title: about save-txt in yolov5-seg
  Body: ### Search before asking
  
  - [X] I have searched the YOLOv5 [issues](https://github.com/ultralytics/yolov5/issues) and [discussions](https://github.com/ultralytics/yolov5/discussions) and found no similar questions.
  
  
  ### Question
  
  when activating "save-txt" in yolov5-seg.py, a txt with the coordinates of the predicted region is saved, but i found that the coordinates seem not to be in sequence, that is to say when i use fillpoly in opencv, the coordinates seem unable to form a polygon like the one of prediction. is there a way to make the coordinates in sequence?
  
  我发现启用save-txt后保存的包含预测分割区域的txt里的坐标似乎不是按顺序的（指坐标的保存顺序不是围着分割区域的）？用opencv的fillpoly填充出来的也跟预测的区域不一样。有办法把坐标变成按顺序的吗？
  
  ![QQ20240923-174819](https://github.com/user-attachments/assets/c991dea0-47bf-4dc1-93cb-d79697ce0493)
  
  ### Additional
  
  _No response_