Fixed guzzle version makes this un-installable

[vesper8]

Hi there,

First of all thanks for making this and sharing it on Github : ) It's just what I'm looking for.

I see you recently fixed the guzzle version to 6.5.5. I imagine it's because you ran into an issue on your own project, related to the Mautic API?

Can I ask what issue this is? Fixing the guzzle version might work in your own project but it makes this un-installable in mine, and I imagine, many other projects. Even the default Laravel 8 install requires Guzzle ^7.01.

Perhaps whatever issue you're running into can be resolved?