Consider migrating CI from CircleCI to GitHub Actions

[Riccardo M. Cefala]

Currently CI is implemented using CircleCI. It does what it needs to, but GitHub actions would give us a better integration and visibility.

Plus is a good exercise :)

[Brendan Kamp]

I'll take this if you guy don't mind 🤷

[Lucas Severo Alves]

Initial work is done. The Helm and integration test part can come in another issue.