Remove normalize argument when creating sklearn solvers

[santisoler]

The normalize argument in the sklearn's LinearRegression and Ridge
classes has been deprecated since version 1.0.0.

Reminders:

• Run make format and make check to make sure the code follows the style guide.
• Add tests for new features or tests that would have caught the bug that you're fixing.
• Add new public functions/methods/classes to doc/api/index.rst and the base __init__.py file for the package.
• Write detailed docstrings for all functions/classes/methods. It often helps to design better code if you write the docstrings first.
• If adding new functionality, add an example to the docstring, gallery, and/or tutorials.
• Add your full name, affiliation, and ORCID (optional) to the AUTHORS.md file (if you haven't already) in case you'd like to be listed as an author on the Zenodo archive of the next release.

[leouieda]

😢 seems like newer versions of dependencies are breaking on Python 3.6. I think it's time we ditch it to be honest. We could have done so a few years back already.

But I don't think we should require the very latest scikit-learn. See fatiando/community#40

From the docs of scikit-learn v0.22, the default is normalize=False anyway. I'm not sure why I set it explicitly here. So you could unpin scikit-learn and just remove the normalize argument to fix the error.

[santisoler]

Thanks for the comment.

😢 seems like newer versions of dependencies are breaking on Python 3.6. I think it's time we ditch it to be honest. We could have done so a few years back already.

Sound fair. We should do that on a separate PR.

But I don't think we should require the very latest scikit-learn. See fatiando/community#40

From the docs of scikit-learn v0.22, the default is normalize=False anyway. I'm not sure why I set it explicitly here. So you could unpin scikit-learn and just remove the normalize argument to fix the error.

I agree. I took a very conservative choice, but now that you mention it, it's better to not pin scikitlearn.

[leouieda]

Thanks!