bump: sbt-header 5.7.0 (was 5.6.5) (#191)

Author: scala-steward

project/plugins.sbt

@@ -1,6 +1,6 @@
 addSbtPlugin("com.github.sbt" % "sbt-pgp" % "2.1.2")
 addSbtPlugin("org.scalameta" % "sbt-scalafmt" % "2.4.6")
-addSbtPlugin("de.heikoseeberger" % "sbt-header" % "5.6.5")
+addSbtPlugin("de.heikoseeberger" % "sbt-header" % "5.7.0")
 addSbtPlugin("com.dwijnand" % "sbt-dynver" % "4.1.1")
 addSbtPlugin("com.github.sbt" % "sbt-ci-release" % "1.5.10")