Coordinate updates if multiple versions of the same dependency are used

[fthomas]

If a project uses multiple versions of the same dependency, Scala Steward does a bad job at handling them in a coordinated fashion which results in bad PRs like circe/circe-jackson#36 or scala/scala-collection-compat#432. This is a common situation for projects that support multiple Scala versions or when a project provides integration for multiple versions of another library (e.g. circe-jackson25, circe-jackson26, etc.).

[fthomas]

One way to improve the situation here is by preventing "overtaking" updates. Suppose a project depends on two versions of scala-library:

"org.scala-lang" % "scala-library" % "2.12.13"
"org.scala-lang" % "scala-library" % "2.13.5"

Scala Steward checks each dependency individually for updates. It finds an update for the first dependency from 2.12.13 -> 2.13.5 but none for the second since that is already on the latest version. It then creates a PR for this update which is the reason for the bad PRs above.

I propose we discard the update because it "overtakes" the second dependency. An update is overtaking if there exists another dependency with the same groupId and artifactId but a version that is greater than the update's current version (2.13.5 is greater than 2.12.13) and smaller or equal to the update's next version (2.13.5 is equal to 2.13.5).

This will prevent updates of scala-library 2.12.13 until there is a newer 2.12 version available or the project removes the 2.13.5 dependency.