forgot to update release date

Author: arshaw

_includes/topbar.html

@@ -65,7 +65,7 @@
 
     <div class='topbar__notice'>
       <a class='topbar__notice-link' href='https://github.com/fullcalendar/fullcalendar/releases' target='_blank'>
-        <span style="color: #FAC863">Feb 20</span> &mdash;
+        <span style="color: #FAC863">May 22</span> &mdash;
         v{{ site.data.latest-releases.v6 }}
       </a>
       {% comment %}