Get rid of docker dependency

[Termina1]

Hi,

It looks like you're using github.com/docker/docker only in one file within tests, but it is required dependency, so using it for my migration scripts will bring whole docker into my go.sum.

Would you may be consider vendoring those deps for example or somehow isolate docker from the main go.mod?

This problem got my attention when I saw dependabot alert about vulnerability in my project and I was surprised that I have containerd as my dep.

[SuperSandro2000]

This can be closed with the latest release and specifically #815