Update sbt-ghpages to 0.8.0

Author: scala-center-steward[bot]

project/plugins.sbt

@@ -1,6 +1,6 @@
 addSbtPlugin("com.github.sbt" % "sbt-ci-release" % "1.5.11")
 addSbtPlugin("com.eed3si9n" % "sbt-buildinfo" % "0.11.0")
-addSbtPlugin("com.github.sbt" % "sbt-ghpages" % "0.7.0")
+addSbtPlugin("com.github.sbt" % "sbt-ghpages" % "0.8.0")
 addSbtPlugin("ch.epfl.scala" % "sbt-version-policy" % "2.1.0")
 addSbtPlugin("org.scalameta" % "sbt-mdoc" % "2.3.7")
 addSbtPlugin("org.scoverage" % "sbt-scoverage" % "2.0.7")