Getswish

Added

- Added the undocumented Payout field callbackIdentifier that is
included when retrieving payout updates and only in production environment.

Added

- Added logging.
- Added nox as optional dependency.

Changed

- Updated documentation.
- Updated tests for coverage.

Changed

- Updated production environment default url.
- Updated default test environment parameters.
- Corrected project source url in pyproject.toml.

Added

- Added nox.

Changed

- Updated documentation, build and testing.

Changed

- Updated build, CHANGELOG.md and README.md.

- Added test cases.