fix(blog): 更新 Python 入门系列第四篇的封面图片

Author: qlAD

apps/gkBlog/src/pages/blog/python-beginner-04/index.mdx

@@ -13,7 +13,7 @@ cover: https://cdn.qladgk.com/images/20250927192125481.png
 import Image from "@/components/mdx/Image";
 
 <Image
-  src="https://cdn.qladgk.com/images/20250923161428237.png"
+  src="https://cdn.qladgk.com/images/20250927192125481.png"
   alt="cover"
   width={999}
   height={527}