Update sbt-unidoc to 0.6.1 (#549)

Author: scala-steward

project/plugins.sbt

@@ -7,7 +7,7 @@ addSbtPlugin("org.scala-js"       % "sbt-scalajs"              % "1.20.1")
 addSbtPlugin("org.portable-scala" % "sbt-scalajs-crossproject" % "1.3.2")
 addSbtPlugin("io.shiftleft"       % "sbt-ci-release-early"     % "2.1.11")
 addSbtPlugin("com.47deg"          % "sbt-microsites"           % "1.4.4")
-addSbtPlugin("com.github.sbt"     % "sbt-unidoc"               % "0.6.0")
+addSbtPlugin("com.github.sbt"     % "sbt-unidoc"               % "0.6.1")
 
 addSbtPlugin("com.github.sbt" % "sbt-ci-release" % "1.11.2")
 addSbtPlugin("com.github.sbt" % "sbt-pgp"        % "2.3.1")