Update sbt-jmh to 0.4.8

Author: scala-steward

project/plugins.sbt

@@ -6,4 +6,4 @@ addSbtPlugin("com.typesafe.sbt"   % "sbt-git"                  % "1.0.2")
 addSbtPlugin("org.portable-scala" % "sbt-scalajs-crossproject" % "1.3.2")
 addSbtPlugin("org.scala-js"       % "sbt-scalajs"              % "1.11.0")
 addSbtPlugin("org.scalameta"      % "sbt-mdoc"                 % "2.3.6")
-addSbtPlugin("pl.project13.scala" % "sbt-jmh"                  % "0.4.5")
+addSbtPlugin("pl.project13.scala" % "sbt-jmh"                  % "0.4.8")