Automate the release on a new Scala version

[adpi2]

Because sbt depends on eval, we need to release it each time we want to update the Scala version in sbt. I assume eval is released manually. I wish we could automate it using a Github workflow.

Something like this should work:

1. Add a workflow to manually trigger a release of eval
2. Add Scala version as an input of the workflow
3. Use a environment variable to change the Scala version in the build:

ThisBuild / scalaVersion := Option(System.getenv("SCALA_VERSION")).getOrElse("3.3.1")