joblib no longer included in scikit-learn

[lcreteig]

sklearn.externals.joblib was deprecated in v0.21 and has been removed in v0.23 of scikit-learn (the latest stable release).

Therefore this line in stability_selection.py: from sklearn.externals.joblib import Parallel, delayed will throw an ImportError

P.S. Thanks for making this available! It was really easy to get started with the code, and I learned a lot from the accompanying blog post.