update highlight.js (#6658)

public/vendor/VERSIONS

 Version: 4.2.0
 
 File(s): /vendor/plugins/highlight/highlight.pack.js
-Version: 9.6.0
+Version: 2b46620c9d62e9becf5f25969b5ccc41fa1da470
 
 File(s): /vendor/plugins/jquery.datetimepicker/jquery.datetimepicker.js
 Version: 2.4.5

public/vendor/librejs.html

         </tr>
         <tr>
           <td><a href="./plugins/highlight/highlight.pack.js">highlight.pack.js</a></td>
-          <td><a href="https://github.com/isagalaev/highlight.js/blob/master/LICENSE">BSD 3-Clause</a></td>
-          <td><a href="https://github.com/isagalaev/highlight.js/archive/9.6.0.tar.gz">highlight.js-9.6.0.tar.gz</a></td>
+          <td><a href="https://github.com/highlightjs/highlight.js/blob/master/LICENSE">BSD 3-Clause</a></td>
+          <td><a href="https://github.com/highlightjs/highlight.js/archive/2b46620c.tar.gz">highlight.js-2b46620c.tar.gz</a></td>
         </tr>
         <tr>
           <td><a href="./plugins/jquery.datetimepicker/jquery.datetimepicker.js">jquery.datetimepicker.js</a></td>