Fallback for JSON dumping datetime.

ticdesk_events/views.py

@@ -104,7 +104,7 @@ def register_event(request, cn):
         message.body += form_to_text_table(register_form, 78)
 
         # Attach raw form data as attachment
-        message.attach('register_form.json', json.dumps(register_form.cleaned_data, indent=4), 'application/json')
+        message.attach('register_form.json', json.dumps(register_form.cleaned_data, indent=4, default=str), 'application/json')
 
         # Send message
         message.send()