django2.2: replace removed is_anonymous() and is_authenticated to their now used counterparts

core/templates/core/login.jinja

@@ -11,7 +11,7 @@
 {% endif %}
 
 {% if next %}
-    {% if user.is_authenticated() %}
+    {% if user.is_authenticated %}
     <p>{% trans %}Your account doesn't have access to this page. To proceed,
     please login with an account that has access.{% endtrans %}</p>
     {% else %}