replace all sklearn -> scikit-learn

[casperdcl]

Quite a few instances in https://github.com/search?l=Text&q=org%3Aiterative+sklearn&type=Code

See e.g. iterative/example_cml#256, iterative/cml_dvc_case#23

[tasdomas]

Is there really a supply chain issue here? sklearn is a dummy package that specifies scikit-learn as its only dependency. Sure, it's just a workaround for the import and package name mismatch in scikit-learn, but apart from the additional sklearn==0.0 line in the output of pip freeze there's no significant issue.

[dacbd]

shot in the dark, but there have been a few issues of users asking for support on discord that has stemmed from pip install issues and sk[scikit-]learn versions, so if this is related to that 👍

[casperdcl]

yes, we should fix it since it looks like the dummy package doesn't always install properly