Arf implementation

[robsdavis]

Description

Implementation of the Adversarial Random Forest method using arfpy. It is implemented as a generative model plugin.

Affected Dependencies

Adds the dependancy arfpy. The arfpy license has now been changed to MIT, so it is now compatible with synthcity's licence with no changes.

arfpy requires python >=3 .8, so this PR drops python 3.7 support. Two weeks before the its offial end of life according to https://endoflife.date/python. The previous release can still be used for python 3.7 support.

How has this been tested?

• Tests analogous to the other generative model plugins. Available at the following file path: tests/plugins/generic/test_arf.py.

Checklist

• I have followed the Contribution Guidelines and Code of Conduct
• I have commented my code following the van der Schaar Lab Styleguide
• I have labelled this PR with the relevant Type labels
• My changes are covered by tests