Make send method async-able

[ghost]

Hello,

I would like to connect send multiple messages, possibly to multiple Teams.
Is it possible to offer an alternative async send?

[rveachkc]

This has already been discussed in #71, so I'm going to mark as duplicate and close.

Async is currently a bit out of scope of this library, but I wouldn't be opposed to adding it. Pull request welcome. I think it's definitely been long enough that I'm ok with dropping python 2 support at this point.