Bump to Scala 2.12.13 and 2.13.4 (bp #2053)

[mergify]

This is an automatic backport of pull request #2053 done by Mergify.

Cherry-pick of e323094 has failed:

On branch mergify/bp/1.4.x/pr-2053
Your branch is up to date with 'origin/1.4.x'.

You are currently cherry-picking commit e3230941.
  (fix conflicts and run "git cherry-pick --continue")
  (use "git cherry-pick --skip" to skip this patch)
  (use "git cherry-pick --abort" to cancel the cherry-pick operation)

Changes to be committed:
	modified:   project/plugins.sbt

Unmerged paths:
  (use "git add <file>..." to mark resolution)
	both modified:   build.sbt

To fixup this pull request, you can check out it locally. See documentation: https://help.github.com/articles/checking-out-pull-requests-locally/

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