Please don't rely on httpguzzle directly

[pscheit]

Since the repo does require to use guzzle 6, it's hard to upgrade.

Better rely on the psr client interface for http clients and let the people plug in guzzle 6 or 7 or symonfy http client

thanks so much
philipp

[pkopac]

Thank you for pointing this out. We're releasing this as a major version change here:
https://github.com/chartmogul/chartmogul-php/releases/tag/3.0.0