Replace Travis CI with GitHub Actions

[rhysd]

Travis CI workflow is no longer working. This PR replaces it with GitHub Actions CI workflow.

The CI workflow checks:

• npm test with all Node.js LTS releases (v14, v16, v18)
• npm run lint

Here is an example of workflow result: https://github.com/rhysd/json5/actions/runs/2438401038

[aseemk]

Excellent, thank you!

[aseemk]

(@jordanbtucker: let me know if you had any concerns/hesitations with this!)

[jordanbtucker]

Is there a benefit of moving to GitHub Actions over Travis CI? I haven't learned how to use GitHub Actions yet.

[rhysd]

@jordanbtucker Travis CI was no longer working. https://travis-ci.com/json5/json5 is 404.

[jordanbtucker]

I believe we just needed to change the URLs. Travis CI was working up until this merge.

[jordanbtucker]

@rhysd Thank you for your contribution, however I reverted these changes as I am not ready to switch to a CI platform I'm not familiar with. I fixed the issues with Travis CI (#280, #281), so I will continue using that for the time being.

[rhysd]

OK, I understood.