fix goblin logo

Author: canertol

blog/2023-10-23-goblin.md

@@ -5,7 +5,7 @@ authors: ['mhashemi']
 ---
 
 <p align="center">
-  <img src="/img/Goblin_logo.PNG" alt="Goblin Logo" width="250" />
+  <img src="/img/Goblin_logo.png" alt="Goblin Logo" width="250" />
 </p>
 
 ### What are the incredible features of Goblin?