Distribute in the GitHub Actions Marketplace

[MoralCode]

I feel like having this available in the GitHub Actions Marketplace would make it easy for people to add Flet build workflows to their existing actions configs.

Here are the docs

This could be combined with other actions that already exist in the marketplace to take the built artifacts and upload them as a release, or ship them somewhere (potentially addressing #5)

[ndonkoHenri]

Thanks, will have a look when possible.

[NHLOCAL]

This is an excellent idea, I also agree with the request