Move CI to Github Actions

[speedytwenty]

To address #271, this incorporates a github action which should run the tests across the same [major] versions of node as was previously setup with Travis.

[Attempting this PR from a non-fork branch to attempt to induce the action]

[speedytwenty]

Waiting for a review or feedback before merging because I'm not entirely confident on the use of npm instead of yarn in the actions commands. It's likely trivial, but I wasn't able to use the npm ci command—which presumably has some efficiency benefits—because it seemed to demand a package-lock.json file.

Also noting, that I'm not sure that the badge in the readme is correct. We might tweak the profile name now that I see it's used by the badge: https://github.com/cli-table/cli-table3/blob/5dd0a6cf00b314e424f55ae46e0db3fa58bfeb41/README.md

[speedytwenty]

Alright, I renamed the action to read "Build" in the badge (and squashed commits). It should come up with a status once it hits master: https://github.com/cli-table/cli-table3/blob/5dd0a6cf00b314e424f55ae46e0db3fa58bfeb41/README.md

[DanielRuf]

yarn is also available on GHA by default, if we need this. Yes, npm clean-install requires a lock file like yarn does for reproducible builds.

[speedytwenty]

Good to know. Thanks!

I adjusted the workflow to use yarn instead of npm. I was originally seeing this issue when attempting to use yarn but it looks like it works now.