Fix #1251 -- Event list/calendar: Show "event almost sold out" state (#3063)

Co-authored-by: Richard Schreiber <schreiber@rami.io>

src/pretix/control/forms/event.py

@@ -507,6 +507,7 @@ class EventSettingsForm(SettingsForm):
         'meta_noindex',
         'redirect_to_checkout_directly',
         'frontpage_subevent_ordering',
+        'low_availability_percentage',
         'event_list_type',
         'event_list_available_only',
         'frontpage_text',

src/pretix/control/templates/pretixcontrol/event/settings.html

@@ -314,7 +314,8 @@
                 {% if sform.event_list_available_only %}
                     {% bootstrap_field sform.event_list_available_only layout="control" %}
                 {% endif %}
-                
+                {% bootstrap_field sform.low_availability_percentage layout="control" %}
+
                 {% url "control:organizer.edit" organizer=request.organizer.slug as org_url %}
                 {% propagated request.event org_url "meta_noindex" %}
                     {% bootstrap_field sform.meta_noindex layout="control" %}