PSR-18 Support

[sylfabre]

Hello

Your library is fantastic for using Plaid out of the box 💪

However, it forces the use of https://github.com/nimbly/Shuttle

• The required major version is 0 meaning it is still in the initial development stage
• It forces the use of this given PSR-18 implementation

Could you please consider simply requiring the psr/http-client-implementation and psr/http-factory-implementation virtual packages so that every application implementing Plaid is free to use whatever PSR-18 implementation they feel like?

More about it: https://jiripudil.cz/blog/do-not-bring-your-own-http-client

Thank you!

[brentscheffler]

Definitely a possibility.