Replace — with literal emdash

cms/templates/activation_invalid.html

@@ -17,7 +17,7 @@
       <div class="msg">
         <h1 class="title">${_("Your account activation is invalid")}</h1>
         <div class="copy">
-          <p>${_("We're sorry. Something went wrong with your activation. Check to make sure the URL you went to was correct &mdash; e-mail programs will sometimes split it into two lines.")}</p>
+          <p>${_("We're sorry. Something went wrong with your activation. Check to make sure the URL you went to was correct — e-mail programs will sometimes split it into two lines.")}</p>
           <p>${_("If you still have issues, contact edX Support. In the meantime, you can also return to {link_start}the Studio homepage.{link_end}").format(
               link_start='<a href="/">', link_end="</a>"
             )}</p>