Color validations

[saroad2]

Add color constructor validations in order to make sure that rgb and hsl objects are constructed with valid values.

[saroad2]

This PR fail on towncrier.check. I'm not sure what the right thing to do in order to fix the error. Just run towncrier?

[freakboy3742]

Towncrier is a recent addition; it's a way of making sure that our release notes stay up to date. It ensures that every pull request that is merged must have a release note describing the feature/bug/etc that the PR implements.

The test will pass if there is a single new file in the changes folder with the name 17.bug.rst (or 17.feature.rst for a new feature, or 17.doc.rst for new docs, or 17.removal.rst for a feature that has been removed, or 17.misc.rst for miscellaneous admin that isn't release note worthy). You don't need to run anything; you only need to add a file to the changes directory.

[saroad2]

On it 👍

[freakboy3742]

Looks like solid changes.

The tests are all good, but they really do have me pining for pytest parametrization... That's no reason to block on this PR, but it's yet another reason to start making that change.