fix: .less instead of .css

This was causing issues, as the linter could not find the proper file. I
think we should probbaly change the template file to be `.less` to
prevent future recurrences of this issue.

Author: arithefirst

styles/t3-chat/catppuccin.user.css styles/t3-chat/catppuccin.user.less

@@ -3,7 +3,7 @@
 @namespace github.com/catppuccin/userstyles/styles/t3-chat
 @homepageURL https://github.com/catppuccin/userstyles/tree/main/styles/t3-chat
 @version 0.0.1
-@updateURL https://github.com/catppuccin/userstyles/raw/main/styles/t3-chat/catppuccin.user.css
+@updateURL https://github.com/catppuccin/userstyles/raw/main/styles/t3-chat/catppuccin.user.less
 @supportURL https://github.com/catppuccin/userstyles/issues?q=is%3Aopen+is%3Aissue+label%3At3-chat
 @description Soothing pastel theme for T3 Chat
 @author Catppuccin