Update scikit-learn to 0.21.2

[pyup-bot]

This PR updates scikit-learn from 0.20.0 to 0.21.2.

Changelog

0.21.2

This version fixes a few bugs released in 0.21.1.

0.21.1

See changes at https://scikit-learn.org/0.21/whats_new/v0.21.html

Fixes some packaging issues in version 0.21.0 along with a few bugs.

0.21.0

A new release of Scikit-learn with many new features, enhancements and bug fixes. See https://scikit-learn.org/0.21/whats_new/v0.21.html

0.20.3

A bug-fix release in the 0.20 series, supporting Python 2 and 3

0.20.2

Bug-fix release to the 0.20 branch, supporting Python 2 and 3

0.20.1

Released 21 November 2018.

See changelog at https://scikit-learn.org/0.20/whats_new.htmlversion-0-20-1

Links

• PyPI: https://pypi.org/project/scikit-learn
• Changelog: https://pyup.io/changelogs/scikit-learn/
• Homepage: http://scikit-learn.org