Update sbt-scalafmt to 2.4.6 in main

Author: http4s-steward[bot]

project/plugins.sbt

@@ -12,6 +12,6 @@ addSbtPlugin("com.eed3si9n" % "sbt-buildinfo" % "0.10.0")
 
 addSbtPlugin("com.github.sbt" % "sbt-ci-release" % "1.5.9")
 
-addSbtPlugin("org.scalameta" % "sbt-scalafmt" % "2.4.4")
+addSbtPlugin("org.scalameta" % "sbt-scalafmt" % "2.4.6")
 
 addSbtPlugin("io.github.davidgregory084" % "sbt-tpolecat" % "0.1.20")