GitHub Actions

[aminya]

Description of the change

Use GitHub Actions instead of Travis and Appveyor.

Benefits

• GitHub Actions is much faster than the other CI services and allows parallel runs
• GitHub Actions it is much easier to configure.
• Atom is a GitHub product, so we should use GitHub Actions.
• Travis is making its services limited and monetary.
  https://blog.travis-ci.com/2020-11-02-travis-ci-new-billing

Verification

The CI passes: https://github.com/aminya/language-javascript/actions/runs/359738214

Drawbacks

none

Release Notes

N/A

[icecream17]

(Probably a silly question) Is AppVeyor removed because it's redundant?

[aminya]

Appveyor was being used for testing the code on Windows. But now GitHub Actions has Windows support, we don't need Appveyor anymore.

P.S: Because I don't have access to this organization, I cannot set the "ignore build if no appveyor.yml" option, which disables Appveyor when appveyor.yml is deleted. So I have to use a dummy appveyor.yml to achieve the same thing.