chore: reference demo image from github

Author: lukasbach

readme.md

@@ -5,7 +5,7 @@
 [![](https://badgen.net/bundlephobia/dependency-count/react-complex-tree)](https://bundlephobia.com/package/react-complex-tree)
 [![](https://badgen.net/bundlephobia/minzip/react-complex-tree)](https://bundlephobia.com/package/react-complex-tree)
 
-![Demo for React Complex Tree](./demo.gif)
+![Demo for React Complex Tree](https://raw.githubusercontent.com/lukasbach/react-complex-tree/main/demo.gif)
 
 > An Unopinionated Accessible Tree Component with Multi-Select and Drag-And-Drop