bump: update sbt-scalafix, scalafix-core from 0.11.1 to 0.12.0 (#4362)

Author: scala-steward

project/plugins.sbt

@@ -20,7 +20,7 @@ addSbtPlugin("com.lightbend.sbt" % "sbt-bill-of-materials" % "1.0.2")
 addSbtPlugin("com.lightbend.akka" % "sbt-paradox-akka" % "0.54")
 addSbtPlugin("de.heikoseeberger" % "sbt-header" % "5.10.0")
 addSbtPlugin("net.bzzt" % "sbt-reproducible-builds" % "0.32")
-addSbtPlugin("ch.epfl.scala" % "sbt-scalafix" % "0.11.1")
+addSbtPlugin("ch.epfl.scala" % "sbt-scalafix" % "0.12.0")
 addSbtPlugin("com.github.sbt" % "sbt-ci-release" % "1.5.12")
 
 // used in ValidatePullRequest to check github PR comments whether to build all subprojects