Update sbt-ci-release to 1.5.12

Author: scala-steward

project/plugins.sbt

@@ -1,6 +1,6 @@
 resolvers += Resolver.bintrayIvyRepo("sbt", "sbt-plugin-releases")
 
-addSbtPlugin("com.github.sbt"    % "sbt-ci-release"  % "1.5.10")
+addSbtPlugin("com.github.sbt"    % "sbt-ci-release"  % "1.5.12")
 addSbtPlugin("com.typesafe"      % "sbt-mima-plugin" % "1.0.1")
 addSbtPlugin("de.heikoseeberger" % "sbt-header"      % "5.6.5")
 addSbtPlugin("org.scalameta"     % "sbt-scalafmt"    % "2.4.6")