Added Async HTTP

[Roman505050]

Synchronous code has been rewritten to be asynchronous, which gives users a lot of power. Because the majority of applications currently use asynchrony, which allows you to perform several actions at the same time and is an integral part of any project in process optimization.

The asyncio package was created in which the _V5AHTTP Manager class was rewritten to be asynchronous using the aiohttp library. The classes that follow this class were partially changed, namely, await was added during the request and an asynchronous function was made. Created file unified_trading.py in which only HTTP was implemented, just like you did, but already completely asynchronous.

I hope my contribution to this project will be useful.