update: optimize the action code for writing tutorials.

examples/write_tutorial.py

@@ -1,10 +1,12 @@
 #!/usr/bin/env python3
 # _*_ coding: utf-8 _*_
+
 """
 @Time    : 2023/9/4 21:40:57
 @Author  : Stitch-z
 @File    : tutorial_assistant.py
 """
+
 import asyncio
 
 from metagpt.roles.tutorial_assistant import TutorialAssistant