events: fix missing send_once param from api

Signed-off-by: Jens Langhammer <jens.langhammer@beryju.org>

authentik/events/api/notification_transport.py

@@ -36,6 +36,7 @@ class NotificationTransportSerializer(ModelSerializer):
             "mode",
             "mode_verbose",
             "webhook_url",
+            "send_once",
         ]
 
 

swagger.yaml

@@ -15203,6 +15203,11 @@ definitions:
       webhook_url:
         title: Webhook url
         type: string
+      send_once:
+        title: Send once
+        description: Only send notification once, for example when sending a webhook
+          into a chat channel.
+        type: boolean
   NotificationTransportTest:
     description: Notification test serializer
     required: