Update sbt-ci-release to 1.5.6

Author: 47erbot

project/plugins.sbt

@@ -1,7 +1,7 @@
 addSbtPlugin("com.eed3si9n"              % "sbt-buildinfo"            % "0.10.0")
 addSbtPlugin("org.scalameta"             % "sbt-mdoc"                 % "2.2.14")
 addSbtPlugin("org.scalameta"             % "sbt-scalafmt"             % "2.4.2")
-addSbtPlugin("com.geirsson"              % "sbt-ci-release"           % "1.5.5")
+addSbtPlugin("com.geirsson"              % "sbt-ci-release"           % "1.5.6")
 addSbtPlugin("de.heikoseeberger"         % "sbt-header"               % "5.6.0")
 addSbtPlugin("com.alejandrohdezma"       % "sbt-github"               % "0.9.1")
 addSbtPlugin("com.alejandrohdezma"       % "sbt-github-header"        % "0.9.1")