remove twitter link (musk bad xD)

input/contact.md

 You can always use this [PGP Key](files/xythobuz.asc)!
 
 * Mail: <thomas@xythobuz.de>
-* Twitter: [@xythobuz](https://twitter.com/xythobuz)
 * Youtube: [xythobuz](http://www.youtube.com/user/xythobuz)
 * Printables [xythobuz](https://www.printables.com/social/216011-xythobuz)
 * Thingiverse: [xythobuz](https://www.thingiverse.com/xythobuz/designs)