Support for CancellationToken

[aakashsethi20]

Hey @JohnnyCrazy!

First of all, I just want to thank you for your amazing work and effort to open-source a useful library.

I wanted to ask if there are any plans to support CancellationToken in API requests? It's not a huge deal but I've noticed that sometimes my application will still go out and call Spotify API even when a request has been canceled by the client (user moving to a different page or something else).

I think we could provide the user of this library with an Async/Await implementation that supports things like CancellationToken. What do you think?