Update Transmission to 4.0.6

Dear Ultra.cc team, it would be greatly appreciated to have Transmission updated to version 4.0.6. It is a bugfix-only release, therefore it looks super safe and straightforward to deploy, and as I could see in the changelog, one quite annoying bug seems to have been fixed now, regarding uTP protocol not following speed limits properly - please refer to “UTP peer connections follow user-defined speed limits better now. (#6551)”.

That may open some room to allow having Transmission 4.1.0 as beta, which is IMHO the cherry in the cake here: less CPU and memory footprint, better DHT ad uTP performance, among other overall improvements, maybe surpassing other popular torrent clients.

Thank you!