Updated sklearn dependency with official package

[gillesoldano]

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)
• Docs change / refactoring / dependency upgrade

Motivation and Context / Related issue

It replaces the deprecated,unofficial "sklearn" dependency with "scikit-learn"

#454

How Has This Been Tested (if it applies)

I have run the test suite with the command python3 -u -m unittest discover -s test -p '*test*.py'

Checklist

• The documentation is up-to-date with the changes I made.
• I have read the CONTRIBUTING document and completed the CLA (see CONTRIBUTING).
• All tests passed, and additional code has been covered with new tests.

Attached are the Dockerfile of the image I used to run the test suite and the test outputs
Dockerfile.txt
err.txt
out.txt