events: fix destination_group_obj not being nullable (#22161)

* events: fix `destination_group_obj` not being nullable

* `make lint-fix`

authentik/events/api/notification_rules.py

@@ -11,7 +11,9 @@ from authentik.events.models import NotificationRule
 class NotificationRuleSerializer(ModelSerializer):
     """NotificationRule Serializer"""
 
-    destination_group_obj = GroupSerializer(read_only=True, source="destination_group")
+    destination_group_obj = GroupSerializer(
+        read_only=True, source="destination_group", required=False, allow_null=True
+    )
 
     class Meta:
         model = NotificationRule

packages/client-ts/src/models/NotificationRule.ts

@@ -58,7 +58,7 @@ export interface NotificationRule {
      * @type {Group}
      * @memberof NotificationRule
      */
-    readonly destinationGroupObj: Group;
+    readonly destinationGroupObj: Group | null;
     /**
      * When enabled, notification will be sent to user the user that triggered the event.When destination_group is configured, notification is sent to both.
      * @type {boolean}

schema.yml

@@ -43829,6 +43829,7 @@ components:
           allOf:
           - $ref: '#/components/schemas/Group'
           readOnly: true
+          nullable: true
         destination_event_user:
           type: boolean
           description: When enabled, notification will be sent to user the user that