fix: dead link for httpie

Update dead link to GIF animation for the httpie project

Author: pReya

README.md

@@ -238,7 +238,7 @@
  </h1>
  <p align="center">A modern, user-friendly command-line HTTP client for the API era.</p>
  <p align="center">
- <img src="https://raw.githubusercontent.com/httpie/httpie/master/httpie.gif" width="600" />
+ <img src="https://raw.githubusercontent.com/httpie/httpie/master/docs/httpie-animation.gif" width="600" />
  </p>
 </p>