Which open source ticket system to choose according to the specified requirements?

Question

Helpdesk

We need a simple open source ticket system. So far, I spent about a day searching, but, unfortunately, almost everything that I tried did not work. osTicket came up well, but, as they say, I would like to see everyone)
In general, we need a system to work with user requests. The most necessary features: so that the user can create a request / requests, receive a response from the staff, write something of his own in response.
Minimum:
- Open source (some things 100% will have to be added)
- Registration of a new user when making an application (django-helpdesk for example, after creating an application, only allows the user to monitor its execution, but not write anything in response)
- Ability to configure queues. So that the user can choose where exactly the application is sent
Additionally:
- Uploading files to tickets.
- Notifying users via mail
- The language is preferably python, php will do (ruby at worst, the main thing is not perl =)
Please advise something =)