fix: change marketo form submission URL (#5668)

Author: edisile

templates/partials/_newsletter-signup.html

@@ -2,7 +2,7 @@
   <h5 class="p-muted-heading">Newsletter Signup</h5>
   <hr class="u-sv1" />
     <div class="p-card__content js-newsletter-signup">
-        <form action="https://pages.canonical.com/index.php/leadCapture/save" method="post" class="p-form" id="mktoForm_3376">
+        <form action="https://ubuntu.com/marketo/submit" method="post" class="p-form" id="mktoForm_3376">
             <div class="p-form__group">
                 <label for="Email" class="u-no-padding--top">Email:*</label>
                 <input id="Email" name="Email" maxlength="255" type="email" required />
@@ -28,7 +28,7 @@ <h5 class="p-muted-heading">Newsletter Signup</h5>
             <input type="hidden" name="subId" value="" />
             <input type="hidden" name="munchkinId" value="066-EOV-335" />
             <input type="hidden" name="lpurl" value="" />
-            <input type="hidden" name="ret" value="{{host_url[:-1]}}{{path}}?newsletter=true" />
+            <input type="hidden" name="returnURL" value="{{host_url[:-1]}}{{path}}?newsletter=true" />
             <input type="hidden" name="cr" value="" />
             <input type="hidden" name="kw" value="" />
             <input type="hidden" name="q" value="" />