Update sbt-dotty to 0.5.5 (#499)

Author: scala-steward

project/plugins.sbt

@@ -7,4 +7,4 @@ addSbtPlugin("org.scalameta" % "sbt-scalafmt" % "2.4.6")
 addSbtPlugin("com.typesafe" % "sbt-mima-plugin" % "1.0.1")
 addSbtPlugin("ch.epfl.scala" % "sbt-scalafix" % "0.9.34")
 addSbtPlugin("com.github.sbt" % "sbt-ci-release" % "1.5.10")
-addSbtPlugin("ch.epfl.lamp" % "sbt-dotty" % "0.5.4")
+addSbtPlugin("ch.epfl.lamp" % "sbt-dotty" % "0.5.5")