Update Vue mastery banner url (#2918)

* Remove Vueschool banner

* Add Vuemastery winter promotion

* Update baner

Co-authored-by: Evan You <[email protected]>

Author: pieer

themes/vue/layout/partials/vuemastery_banner.ejs

@@ -1,5 +1,5 @@
 <div id="vm-banner" class="vuemastery-banner hide" role="banner">
-  <a href="https://www.vuemastery.com/free-weekend-december-2021" target="_blank">
+  <a href="https://www.vuemastery.com/free-weekend" target="_blank">
     <div class="vuemastery-banner--wrapper">
       <img class="vuemastery-banner--logo" src="/images/logo-vuemastery.svg" alt="vuemastery" />
       <p>Access the ultimate collection of Vue courses free. <span>Dec 17-20</span></p>