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-python/actions/runs/359805292

Drawbacks

none

Release Notes

N/A

[darangi]

Thanks @aminya