Add versionScheme & MiMa

[saeltz]

• Adds versionScheme: early-semver from sbt 1.4.0 which will be enforced with the upcoming sbt 1.5.0 for eviction errors
• Adds mimaReportBinaryIssues plugin to GitHub Actions to ensure sane versioning
• Updates to new moia-oss moved to Change moia-dev to moia-oss #158

I think we don't need to release this as a new version. Maybe as patch release.

Background for versionScheme: https://www.scala-lang.org/blog/2021/02/16/preventing-version-conflicts-with-versionscheme.html

[JannikArndt]

Example for binary-incompatible changes: You can change any public function and then run sbt mimaReportBinaryIssues. It will download the referenced version (4.0.0) from maven.org and compare the functions, yielding an error:

This way we can guarantee to be binary-compatible with the given version for every release.

[JannikArndt]

Great work, thank you! 🙏