Update sbt-ci-release to 1.5.12 (#544)

Author: scala-steward

project/plugins.sbt

@@ -4,7 +4,7 @@ addSbtPlugin("org.portable-scala" % "sbt-scalajs-crossproject" % "1.3.1")
 addSbtPlugin("org.scala-native" % "sbt-scala-native" % "0.4.12")
 addSbtPlugin("org.portable-scala" % "sbt-scala-native-crossproject" % "1.3.1")
 
-addSbtPlugin("com.github.sbt" % "sbt-ci-release" % "1.5.11")
+addSbtPlugin("com.github.sbt" % "sbt-ci-release" % "1.5.12")
 
 addSbtPlugin("org.scalameta" % "sbt-scalafmt" % "2.5.0")