Update sbt-header to 5.7.0 (#2580)

Author: scala-steward

project/plugins.sbt

@@ -6,7 +6,7 @@ addSbtPlugin("org.scalameta" % "sbt-scalafmt" % "2.4.6")
 addSbtPlugin("com.github.cb372" % "sbt-explicit-dependencies" % "0.2.16")
 addSbtPlugin("com.github.tkawachi" % "sbt-doctest" % "0.10.0")
 addSbtPlugin("com.github.sbt" % "sbt-native-packager" % "1.9.9")
-addSbtPlugin("de.heikoseeberger" % "sbt-header" % "5.6.5")
+addSbtPlugin("de.heikoseeberger" % "sbt-header" % "5.7.0")
 addSbtPlugin("io.github.davidgregory084" % "sbt-tpolecat" % "0.2.3")
 addSbtPlugin("pl.project13.scala" % "sbt-jmh" % "0.4.3")
 addSbtPlugin("org.portable-scala" % "sbt-scalajs-crossproject" % "1.2.0")