Change crafatar to mc-heads

https://crafatar.com/avatars/{{ uuid }} doesn't render head layer on the image while https://mc-heads.net/avatar/{{ uuid }} does.

Crafatar: https://cdn.lukynka.cz/zsgh.png
MC-Heads: https://cdn.lukynka.cz/YUbA.png

index.html

@@ -15,7 +15,7 @@
   <!-- Edit this to change staff cards! -->
   <script id="staff-template" type="text/template">
     <div class="staff-card shrink">
-      <img src="https://crafatar.com/avatars/{{ uuid }}">
+      <img src="https://mc-heads.net/avatar/{{ uuid }}">
       <h3>{{ name }}</h3>
       <h4>{{ rank }}</h4>
     </div>