adding proxy logic

[GrandNative]

hi Ali, I am Morteza, I came across this package for one of my projects, for some reason I could not use this package, however, I noticed that you did not consider any logic to use a proxy while Telethon provided this possibility. That's why I decided to add this logic, anyway, you know how difficult life is in Iran :) I tried to add this feature very simply and with the least number of lines. I have another way to do this, which is to use a database and consider a table for the proxy. If you like, we can talk more about this way. This is my first contribution to an open-source project, so if you see a problem in my work, please let me know. and my Telegram ID, in case you want to contact me: @M_grand