Csobclient

Added

* Python 3.11 support
* `nox` integration for tests

Added

* `/payment/refund`
* Validate Cart's total amount with the requested `total_amount`
* Validation for `total_amount` (> 0)

Fixed

* Use production API URL by default

Changed

* Don't allow import from the `csobclient` directly. Use `csobclient.v19` instead

Fixes
* Expect that the "resultCode" may be missing in the response

Changed
* `PaymentInfo` now encapsulates the whole response including `resultCode` and `resultMessage`

Added
* `PaymentInfo.raise_for_result_code` method. Works similar as `requests.raise_for_status`
* `PaymentInfo.ok` property

Added
* `/payment/close`
* Validation for the Cart size
* Enum for payment statuses
* Support for different RSA key access strategies

Added
* Basic working version