Opening the possibility of injecting a PSR-18 compatible HTTP Client

[bbaga]

Using PSR-18 interface instead of hard Guzzle dependency

More context: #32

[bbaga]

Small update with a minor change in Client + readme update

[mghoneimy]

A few things on this, first of all thank you for the contribution, this was very valuable to improving this package! I'm very happy that we are very close to having the package not dependent on a specific client implementation, when I start working on the new major version upgrade I'll make sure that this is part of it.

Also, I just checked Guzzle's next major version (7.0) will implement the PSR-18 client interface, which will make it much easier to integrate into the package without needing the GuzzleAdapter class. It might be a good time to consider working on the next major version actually when Guzzle's 7.0 is out!

Thank you for contribution to this package, if you don't have anything else you'd like to add I'll merge the pull request tomorrow.

[bbaga]

🎉 🥳 🎉

The Guzzle 7 beta is out for a while now so I hope they'll release the real deal soon! It will be awesome.👏

Thanks for being so quick to respond to questions and the PR, it was really nice working with you.