Replace Combinatronics with jsDelivr for github.css

Author: imprs

_includes/head.html

@@ -14,7 +14,7 @@
     <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://combinatronics.io/jwarby/pygments-css/master/github.css" media="" id="highlight_theme_light" />
+    <link rel="stylesheet" href="https://cdn.jsdelivr.net/gh/jwarby/pygments-css/github.css" media="" id="highlight_theme_light" />
 
     {% if page.toc and page.toc.sidebar %}
     <!-- Sidebar Table of Contents -->