[mailman3] Enable Debug mode for staging

Signed-off-by: Michal Konecny <mkonecny@redhat.com>

roles/mailman3/templates/settings.py.j2

@@ -13,7 +13,11 @@ from mailman_web.settings.mailman import *  # noqa: F403
 SECRET_KEY = '{{ mailman_hyperkitty_cookie_key }}'
 
 # SECURITY WARNING: don't run with debug turned on in production!
+{% if env = 'staging' %}
+DEBUG = True
+{% else %}
 DEBUG = False
+{% endif %}
 
 ADMINS = (
      ('HyperKitty Admin', 'abompard@fedoraproject.org'),