feature request: add a warning emoji (⚠️) for any major version updates

[eed3si9n]

Major version updates of the dependencies can have unintended consequences that are time-consuming to reverse and/or fix-forward.

Some recent examples are scala-xml 2.x and slf4j 2.x, both affecting sbt 1.x plugin/build ecosystem. See for example coursier/sbt-coursier#422
In theory, all automatic PRs should be carefully reviewed. But I think people hit merge, trusting that Scala Steward is making the right call.

I wonder if we could add a warning emoji (⚠️) and a note in the PR calling for the attention of the reviewer that they might be cause a downstream "dependency hell"/diamond problem if they hit the merge button.