Mailtrap webhook: remove None defaults

Author: cahna

anymail/webhooks/mailtrap.py

@@ -88,13 +88,13 @@ def esp_to_anymail_event(self, esp_event: MailtrapEvent):
             event_type=event_type,
             timestamp=timestamp,
             message_id=esp_event["message_id"],
-            event_id=esp_event.get("event_id", None),
-            recipient=esp_event.get("email", None),
+            event_id=esp_event.get("event_id"),
+            recipient=esp_event.get("email"),
             reject_reason=reject_reason,
-            mta_response=esp_event.get("response", None),
+            mta_response=esp_event.get("response"),
             tags=tags,
             metadata=custom_variables,
-            click_url=esp_event.get("url", None),
-            user_agent=esp_event.get("user_agent", None),
+            click_url=esp_event.get("url"),
+            user_agent=esp_event.get("user_agent"),
             esp_event=esp_event,
         )