Update sbt-unidoc to 0.6.0 (#5750)

Author: clairemcginty

project/plugins.sbt

@@ -5,7 +5,7 @@ addSbtPlugin("com.eed3si9n" % "sbt-assembly" % "2.3.1")
 addSbtPlugin("com.eed3si9n" % "sbt-buildinfo" % "0.13.1")
 addSbtPlugin("com.github.cb372" % "sbt-explicit-dependencies" % "0.3.1")
 addSbtPlugin("com.github.sbt" % "sbt-avro" % "4.0.1")
-addSbtPlugin("com.github.sbt" % "sbt-unidoc" % "0.5.0")
+addSbtPlugin("com.github.sbt" % "sbt-unidoc" % "0.6.0")
 addSbtPlugin("com.here.platform" % "sbt-bom" % "1.0.27")
 addSbtPlugin("com.lightbend.paradox" % "sbt-paradox" % "0.10.7")
 addSbtPlugin("com.lightbend.sbt" % "sbt-bill-of-materials" % "1.0.2")