Update sbt-scalafmt to 2.5.6

Author: scala-steward

project/plugins.sbt

@@ -4,6 +4,6 @@ addSbtPlugin("com.typesafe" % "sbt-mima-plugin" % "1.1.4")
 addSbtPlugin("org.scoverage" % "sbt-scoverage" % "2.3.1")
 addSbtPlugin("org.scoverage" % "sbt-coveralls" % "1.3.15")
 addSbtPlugin("com.github.sbt" % "sbt-github-actions" % "0.28.0")
-addSbtPlugin("org.scalameta" % "sbt-scalafmt" % "2.5.5")
+addSbtPlugin("org.scalameta" % "sbt-scalafmt" % "2.5.6")
 addSbtPlugin("com.github.sbt" % "sbt-ci-release" % "1.11.2")
 addSbtPlugin("com.eed3si9n" % "sbt-projectmatrix" % "0.11.0")