🐛 Support for ghcr.io in Action

[laurentsimon]

I tried using the image generated by our release workflow.
When using ghcr.io in the action:

runs:
  using: "docker"
  image: "ghcr.io://ossf/scorecard-action:latest"

I got the following error

'ghcr.io://ossf/scorecard-action:latest' should be either '[path]/Dockerfile' or 'docker://image[:tag]'

When trying

runs:
  using: "ghcr.io"
  image: "ghcr.io://ossf/scorecard-action:latest"

I got

Error: System.ArgumentOutOfRangeException: Specified argument was out of the range of valid values. (Parameter ''using: ghcr.io' is not supported, use 'docker', 'node12' or 'node16' instead.')

@naveensrinivasan am I doing something wrong or is docker registry the only registry supported?
cc @azeemshaikh38

[azeemshaikh38]

See image below. 2 things:

1. Looks like we can use a non Docker hub image if needed.
2. We can directly reference Dockerfile and let GitHub actions build and run that image.

I personally prefer option (2) if that can be done. Wdut?

[laurentsimon]

I like option 2 too, which is what I opted for for this #38. If you're OK with the PR, plz LGTM and I'll cut a release to start testing.