Fix the preview image of miles

Author: sglang-bot

blog/2025-11-19-miles.md

@@ -2,7 +2,7 @@
 title: 'Introducing Miles — RL Framework To Fire Up Large-Scale MoE Training'
 author: "RadixArk Team"
 date: "November 19, 2025"
-previewImg: /images/blog/miles/miles.jpg
+previewImg: /images/blog/miles/miles.png
 ---
 
 > *A journey of a thousand miles is made one small step at a time.*