feat: change from sync to async work

[asiman161]

Hello! I started to look Binance rust clients and only this was actual. I saw some issues that users don't want to use this lib because it's sync. (as me. I forked it to fix this problem. I don't want to use workaround. Write my own lib or fork this and fix) Today I don't know why it should work with sync only (historical? then I want to have async version) and I thought that it will be useful to move it to async API.

I checked examples and tests and it works.