Use a prs-7 http client instead of (only) curl

[tacman]

There are many clients that provide throttling, automatic retry, and a host of other goodies. I like the Symfony HttpClient, others like Guzzle.

Instead of making the API calls with curl, would you consider making them with a psr-7 client that the user installs and configures?

Basically, make the client generic, you could even document installing https://github.com/pdeans/http to continue using curl.

Thanks for releasing this. I like having the storage API and the system API all in the same bundle, currently I've installed the bunny storage https://github.com/BunnyWay/BunnyCDN.PHP.Storage where I just made the same request, and https://github.com/ToshY/BunnyNet-PHP, which does use implement the psr7 client interface.