Update sbt-header to 5.7.0 (#73)

Co-authored-by: Kirill A. Korinsky <[email protected]>

Author: scala-steward

project/plugins.sbt

@@ -15,4 +15,4 @@ addSbtPlugin("com.eed3si9n" % "sbt-buildinfo" % "0.11.0")
 addSbtPlugin("com.eed3si9n" % "sbt-assembly" % "1.2.0")
 addSbtPlugin("com.dwijnand" % "sbt-dynver" % "4.1.1")
 addSbtPlugin("org.scalameta" % "sbt-scalafmt" % "2.4.6")
-addSbtPlugin("de.heikoseeberger" % "sbt-header" % "5.6.5")
+addSbtPlugin("de.heikoseeberger" % "sbt-header" % "5.7.0")