docs(readme): updated demo screenshot url

Author: psparwez

README.md

@@ -4,7 +4,7 @@ A sleek and minimal portfolio website built with **Next.js**, showcasing profess
 
 ## 📸 Demo Screenshot
 
-![Image](https://github.com/user-attachments/assets/6606991a-6349-4162-9e1f-deae78222d8d)
+![Image](https://minimal-portfolio-ps.vercel.app/og_banner.jpeg)
 
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