refactor: remove unused styles

Author: mrholek

src/pug/_partials/head.pug

@@ -32,7 +32,6 @@ link(rel='stylesheet' href='css/vendors/simplebar.css')
 link(href='css/style.css', rel='stylesheet')
 
 // We use those styles to show code examples, you should remove them in your application.
-link(rel='stylesheet' href='https://cdn.jsdelivr.net/npm/[email protected]/themes/prism.css')
 link(href='css/examples.css', rel='stylesheet')
 
 // Global site tag (gtag.js) - Google Analytics