Scala 3 and updates

[MateuszKubuszok]

TODO:

• update sbt and migrate from Travis to GH Actions
• migrate from Specs2 to munit
• prepare for Scala 3 migration
• implement Scala 3 macros
• report lack of Scala Native 0.5 to enumeratum (blocker)
  • Scala Native 0.5 lloydmeta/enumeratum#401
• define enumz-chimney module (to handle runtime enums like Enumeration in Chimney)
• migrate documentation from scalatex to mkdocs