Shift4

What's Changed
* added support for idempotency key by mschielmann in https://github.com/shift4developer/shift4-python/pull/2

New Contributors
* mschielmann made their first contribution in https://github.com/shift4developer/shift4-python/pull/2

**Full Changelog**: https://github.com/shift4developer/shift4-python/compare/v2.0.0...v2.1.0

What's Changed
* removing Cross Sales by mguzowski-shift4 in https://github.com/shift4developer/shift4-python/pull/1

New Contributors
* mguzowski-shift4 made their first contribution in https://github.com/shift4developer/shift4-python/pull/1

**Full Changelog**: https://github.com/shift4developer/shift4-python/compare/v1.0.0...v2.0.0

Initial release