Update sbt-ci-release to 1.5.9 (#142)

Author: scala-steward

build.sbt

@@ -9,5 +9,5 @@ developers          := List(Developer("", "", "", url("https://scala-lang.org"))
 
 addSbtPlugin("com.typesafe.sbt" % "sbt-osgi" % "0.9.6")
 addSbtPlugin("de.heikoseeberger" % "sbt-header" % "5.6.0")
-addSbtPlugin("com.geirsson" % "sbt-ci-release" % "1.5.7") // set version, scmInfo, publishing settings
+addSbtPlugin("com.github.sbt" % "sbt-ci-release" % "1.5.9") // set version, scmInfo, publishing settings
 addSbtPlugin("ch.epfl.scala" % "sbt-version-policy" % "2.0.0")  // brings in MiMa

project/plugins.sbt

@@ -1 +1 @@
-addSbtPlugin("com.geirsson" % "sbt-ci-release" % "1.5.7")
+addSbtPlugin("com.github.sbt" % "sbt-ci-release" % "1.5.9")