Move from travis to github actions

[mansona]

Hey folks 👋 I noticed there was a bunch of work to do to get things moved over to octane and also ready for Ember 4.0 and I'm hoping to help out with that effort.

I did notice that PRs aren't running any tests at the moment though 😬 so I though I would move things over to github actions. This is just copy-pasting the latest version from the Ember 4.x blueprints for addons which you can see here: https://github.com/ember-cli/ember-addon-output/blob/master/.github/workflows/ci.yml

[mansona]

Since the github actions won't run on a PR from a fork of the repo (for security reasons) I have also created a PR to master on my fork so you can see them running: mansona#1

[miguelcobain]

Looks good to me!

[mansona]

So it turns out that there are some issues with this PR 🤔 some tests are failing and it looks like they may be flakey

Also the lint step is failing because there are a whole bunch lint rules that essentially haven't been checked in CI for a while. I'm working on implementing lint-to-the-future in a second PR if that is something that you're interested in? (It could be quite useful for us to keep track of some of the conversion work that needs to be done too)

[mansona]

@miguelcobain I've actually updated this PR now with more work to actually get it passing in CI (most things anyway) Can you take another look and let me know if you're happy with it still?

[Subtletree]

Looks awesome! Stoked to have more people on board with modernizing ember-paper!

I have made a quest issue for ember 4 + octance.