Merge pull request #733 from scala-steward/update/sbt-dotty-0.5.1

Update sbt-dotty to 0.5.1

Author: larsrh

project/plugin.sbt

@@ -2,7 +2,7 @@ addSbtPlugin("com.typesafe" % "sbt-mima-plugin" % "0.8.1")
 
 addSbtPlugin("com.jsuereth" % "sbt-pgp" % "2.1.1")
 
-addSbtPlugin("ch.epfl.lamp" % "sbt-dotty" % "0.5.0")
+addSbtPlugin("ch.epfl.lamp" % "sbt-dotty" % "0.5.1")
 
 addSbtPlugin("org.scala-js" % "sbt-scalajs" % "1.3.1")