vendor directory is out of date

[bboreham]

For instance the code has a dependency on github.com/deckarep/golang-set, but this is not in the vendor directory.

Maybe the intention is that everyone should download dependencies via go mod and the vendor directory should be deleted from the repo?

[mogren]

That dependency will be added by #461 once it has been merged, but I think you are right, we should probably rely on go mod for this.

[mogren]

Updated the vendor folder. That said, building in docker uses go mod, I'll update the Readme for #465.