Update: Sorry, I realize now this isn't exactly what you wanted. But I'll leave it here anyway based on feedback in the comments.
I used the structure manipulation scripts provided by AIRSS to generate the conventional cell associated with your primitive cell. I think AIRSS uses Spglib under the hood for this task, so you could probably use Spglib directly if you wanted.
I realize this isn't exactly what you wanted, but I am leaving it here because of the comments requesting for me to undelete the answer.