Added GitHub Sponsors link to README

Author: yasirkula

.github/README.md

@@ -6,7 +6,7 @@
 
 **Discord:** https://discord.gg/UJJt549AaV
 
-**[Support the Developer ☕](https://yasirkula.itch.io/unity3d)**
+**[GitHub Sponsors ☕](https://github.com/sponsors/yasirkula)**
 
 This plugin helps you generate preview textures (thumbnails) for your **GameObjects** or **materials** in **Texture2D** format on the fly.