Update sbt-ci-release to 1.4.31 (#68)

Update sbt-ci-release to 1.4.31

Author: lrytz

build.sbt

@@ -8,4 +8,4 @@ addSbtPlugin("com.typesafe.sbt" % "sbt-osgi" % "0.9.5")
 addSbtPlugin("de.heikoseeberger" % "sbt-header" % "5.2.0")
 addSbtPlugin("com.typesafe" % "sbt-mima-plugin" % "0.6.1")
 addSbtPlugin("com.dwijnand" % "sbt-travisci" % "1.2.0")   // set scalaVersion and crossScalaVersions
-addSbtPlugin("com.geirsson" % "sbt-ci-release" % "1.3.2") // set version, scmInfo, publishing settings
+addSbtPlugin("com.geirsson" % "sbt-ci-release" % "1.4.31") // set version, scmInfo, publishing settings