Update to Support Guzzle 7

[timramseyjr]

Do you have plans to update to guzzle 7?

[pristinesource]

Same issue. My project requires Guzzle 7, but this cannot install with that version.

[durgesh-sahani]

Same error, we are already using Guzzle ^7.* in our project.

You can also try re-running composer require with an explicit version constraint, e.g. "composer require quickbooks/payments-sdk:*" to figure out if any version is installable, or "composer require quickbooks/payments-sdk:^2.1" if you know which you need.