3.1.2-RC3 Release procedure

[Kordyjan]

• Merge Revert "Allow return in tailrec position" #14067 #14744
• Publish artifacts to Maven via CI
  • On release-3.1.2 branch:
    • In Build.scala: Set baseVersion to 3.1.2-RC3
    • In Build.scala: Set previousDottyVersion to 3.1.2-RC2
    • In tasty/src/dotty/tools/tasty/TastyFormat.scala: make sure MajorVersion and MinorVersion are set correctly for the release.
    • Tag the branch as 3.1.2-RC3
• On master:
  • In Build.scala: Set referenceVersion to 3.1.2-RC3
• Announce the release
  • Publish release on GitHub Releases
  • Make an announcement thread on https://contributors.scala-lang.org