Merge pull request #103 from typelevel/update/sbt-typelevel-0.6.6

Update sbt-typelevel, sbt-typelevel-site to 0.6.6

Author: TonioGela

project/plugins.sbt

@@ -1,3 +1,3 @@
-addSbtPlugin("org.typelevel" % "sbt-typelevel"      % "0.6.5")
-addSbtPlugin("org.typelevel" % "sbt-typelevel-site" % "0.6.5")
+addSbtPlugin("org.typelevel" % "sbt-typelevel"      % "0.6.6")
+addSbtPlugin("org.typelevel" % "sbt-typelevel-site" % "0.6.6")
 addSbtPlugin("org.scala-js"  % "sbt-scalajs"        % "1.15.0")