Update dependency org.scalameta:sbt-scalafmt to v2.5.6

Author: renovate[bot]

project/plugins.sbt

@@ -1,6 +1,6 @@
 addSbtPlugin("com.github.sbt" % "sbt-site-paradox" % "1.5.0")
 addSbtPlugin("org.scalameta" % "sbt-mdoc" % "2.3.6")
-addSbtPlugin("org.scalameta" % "sbt-scalafmt" % "2.4.3")
+addSbtPlugin("org.scalameta" % "sbt-scalafmt" % "2.5.6")
 addSbtPlugin("com.typesafe" % "sbt-mima-plugin" % "1.1.3")
 addSbtPlugin("com.github.sbt" % "sbt-ci-release" % "1.5.12")
 addSbtPlugin("ch.epfl.scala" % "sbt-scalafix" % "0.11.0")