Add proxy option for Telegram.

[Aqaao]

Implementing this is simple. The following is the document of python-telegram-bot. Just load proxy url from config.json or
environment variables.
https://github.com/python-telegram-bot/python-telegram-bot/wiki/Working-Behind-a-Proxy

from telegram.ext import ApplicationBuilder

# "USERNAME:PASSWORD@" is optional, if you need authentication:
proxy_url = 'http://USERNAME:PASSWORD@PROXY_HOST:PROXY_PORT'  # can also be a https proxy
app = ApplicationBuilder().token("TOKEN").proxy(proxy_url).get_updates_proxy(proxy_url).build()

[F33RNI]

#160

[F33RNI]

Can u please check?

[Aqaao]

#160

It work well. thank you😘.