Fix login link.

templates/integrations/add_pushover_help.html

@@ -25,7 +25,7 @@
         </p>
 
         <div class="text-center">
-            <a href="{% url 'hc-login' %} %}"
+            <a href="{% url 'hc-login' %}"
                class="btn btn-primary btn-lg">Sign In</a>
         </div>
         {% endif %}