Also added an ml extra dependency which should allow DBR 13, 14 and 15 ML support; this should be installed using koheesio[ml]

Related Issue

#79

Motivation and Context

• Support ML type work
• Allow Transformation type contributions on the pandas module

To do

• Run tests on DBR
• Make an env without ml extra to ensure that koheesio core works as intended
• Make an env without spark to ensure the lib works as intended when not using spark

How Has This Been Tested?

Added unit tests. Integration tests on ML pipelines still needed.

Screenshots (if appropriate):

N/A

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• All new and existing tests passed.