Add license classifier to PyPI/setup.py

[WilliamRoyNelson]

💡 Feature request

PyPI includes classifier tags for things like Operating System, Python version, etc. This package seems to be using the MIT license, but it's not included in the classifiers. Please add the classifier.

Motivation

Automated tools that scan for open vulnerabilities and license issues rely on the classifier tag in order to identify packages that are risky or could create legal liability from licensing. Because the classifier is not present, this leads some tools to assume that there is no license and mark it as a high risk package.

Additional context

I am fairly inexperienced with the PyPI publication process, but I think that it can be done by modifying setup.py and adding
"License :: OSI Approved :: MIT License", to the list of classifiers. Reference: https://pypi.org/classifiers/

[WilliamRoyNelson]

I've made a PR to fix this.
As mentioned in the issue description, I'm a little unsure of how it works, but it's not exactly the sort of thing you can write a unit test for.

#206