Revert "Change gitcdn link (alshedivat#234)" (alshedivat#364)

This reverts commit 0e4df83.

Author: alshedivat

_includes/head.html

@@ -34,7 +34,7 @@
 <link rel="stylesheet" type="text/css" href="https://fonts.googleapis.com/css?family=Roboto:300,400,500,700|Roboto+Slab:100,300,400,500,700|Material+Icons">
 
 <!-- Code Syntax Highlighting -->
-<link rel="stylesheet" href="https://gitcdn.xyz/repo/jwarby/jekyll-pygments-themes/master/{{ site.highlight_theme }}.css" />
+<link rel="stylesheet" href="https://gitcdn.link/repo/jwarby/jekyll-pygments-themes/master/{{ site.highlight_theme }}.css" />
 
 <!-- Styles -->
 {% if site.icon != empty %}