highlight.js update in demo

support/demo_template/index.jade

@@ -14,8 +14,8 @@ html
     script(src='https://cdn.jsdelivr.net/bootstrap/3.2.0/js/bootstrap.min.js')
     link(rel='stylesheet' href='https://cdn.jsdelivr.net/bootstrap/3.2.0/css/bootstrap.css')
 
-    script(src='https://cdn.jsdelivr.net/highlight.js/8.4.0/highlight.min.js')
-    link(rel='stylesheet' href='https://cdn.jsdelivr.net/highlight.js/8.4.0/styles/solarized_light.min.css')
+    script(src='https://cdn.jsdelivr.net/highlight.js/8.5.0/highlight.min.js')
+    link(rel='stylesheet' href='https://cdn.jsdelivr.net/highlight.js/8.5.0/styles/solarized_light.min.css')
 
     script(src='markdown-it.js')
     script(src='https://twemoji.maxcdn.com/twemoji.min.js')