feat: added AnyIO

[pohlt]

What is this project?

From their README: AnyIO is an asynchronous networking and concurrency library that works on top of either asyncio or trio. It implements trio-like structured concurrency (SC) on top of asyncio and works in harmony with the native SC of trio itself.

Applications and libraries written against AnyIO's API will run unmodified on either asyncio or trio. AnyIO can also be adopted into a library or application incrementally – bit by bit, no full refactoring necessary. It will blend in with the native libraries of your chosen backend.

Why is it awesome?

• enables writing code which is agnostic to underlying async library
• allows for structured concurrency