Build should declare a `versionScheme`

[SethTisue]

as per https://scala-lang.org/blog/2021/02/16/preventing-version-conflicts-with-versionscheme.html and discussion at scala/sbt-scala-module#111

[Philippus]

Can we start using "early-semver" from now on, or do we have to take the past into consideration?

[SethTisue]

uh, I'm not sure. off the top of my head my answer would be "from now on only".... but do you have a particular scenario or concern in mind?

[Philippus]

I think we can go with "early-semver" then, from now on. :)

[SethTisue]

fixed by #364