Update sbt-github-pages to 0.15.0

Signed-off-by: Scala Steward <[email protected]>

Author: scala-steward

project/plugins.sbt

@@ -7,7 +7,7 @@ addSbtPlugin("com.github.sbt" % "sbt-git" % "2.1.0")
 addSbtPlugin("com.github.sbt" % "sbt-native-packager" % "1.11.1")
 addSbtPlugin("com.github.sbt" % "sbt-pgp" % "2.3.1")
 addSbtPlugin("com.github.sbt" % "sbt-site" % "1.7.0")
-addSbtPlugin("io.kevinlee" % "sbt-github-pages" % "0.14.0")
+addSbtPlugin("io.kevinlee" % "sbt-github-pages" % "0.15.0")
 addSbtPlugin("nl.gn0s1s" % "sbt-dotenv" % "3.1.1")
 addSbtPlugin("org.scalameta" % "sbt-scalafmt" % "2.5.4")
 addSbtPlugin("org.scoverage" % "sbt-scoverage" % "2.3.1")