Fix usage of xapikey in the kwargs of the methods

[mgu]

Description

Since version 8.0.0

response = adyen_client.terminal.get_terminals_under_account(request, xapikey=api_key)

results in the following error:

TypeError: Adyen.httpclient.HTTPClient._requests_request() got multiple values for keyword argument 'xapikey'

This is because kwargs.pop doesn't remove the key from the kwargs of the caller in the client. Instead of using **kwargs, I pass the dict to functions which will modify it.

Tested scenarios

Tested with the code above.
I would be happy to add a unit test if you tell me where to put it :)

Fixed issue:

[antolo-arch]

Hi @mgu,

Thanks for bringing this to our attention. I've looked into the client and made a small change (#234) that solves the issue.

Thanks again for your contribution! 🚀