Use labeler for consistent labels for the project

[ericwb]

Describe the solution you'd like
Thinking maybe we should adopt labeler found here:
https://github.com/tonglil/labeler
That way we don't have a proliferation of labels and duplicates and each label is clearly defined and explained.

Describe alternatives you've considered
Manual maintenance.

Additional context

[joshuagl]

This looks interesting. The only reservation I have is how to integrate it into our workflow?

• Relying on maintainers manually running this would be bad
• Hooking this into Travis would work, but feels unclean (this isn't really a CI task)

A GitHub Action might work, but they are not yet available.