fix: github assets url (#774)

src/core/render/emojify.js

@@ -1,7 +1,7 @@
 import {inBrowser} from '../util/env'
 
 function replace(m, $1) {
-  return '<img class="emoji" src="https://assets-cdn.github.com/images/icons/emoji/' + $1 + '.png" alt="' + $1 + '" />'
+  return '<img class="emoji" src="https://github.githubassets.com/images/icons/emoji/' + $1 + '.png" alt="' + $1 + '" />'
 }
 
 export function emojify(text) {

src/plugins/emoji.js

@@ -892,7 +892,7 @@ const AllGithubEmoji = [
 window.emojify = function (match, $1) {
   return AllGithubEmoji.indexOf($1) === -1 ?
     match :
-    '<img class="emoji" src="https://assets-cdn.github.com/images/icons/emoji/' +
+    '<img class="emoji" src="https://github.githubassets.com/images/icons/emoji/' +
       $1 +
       '.png" alt="' +
       $1 +