Move from Travis CI to Github Actions

[bwillis]

We're running test via travis, but I'd like to try out Github Actions to see if this is an easier way to manage the CI pipeline.

Outcome

When comparing Github Actions to Travis, Github Actions completed much quicker:

Not a lot of data points, but Travis took (total time) 12m/13m and Github actions steps all completed in 1m 🤯.

I'm going to make the decision to switch over based on:

• Speed of execution - Increases developer productivity
• Reduction of dependencies - remove Travis CI as a dependency, easier to maintain

[coveralls]

Coverage remained the same at 100.0% when pulling 085be2b on github-actions into 84e4dd8 on master.