Update sbt-scalafix to 0.9.29 (#2155)

Author: scala-steward

modules/core/src/main/scala/org/scalasteward/core/buildtool/sbt/package.scala

@@ -38,7 +38,7 @@ package object sbt {
   val scalaStewardScalafixSbt: FileData =
     FileData(
       "scala-steward-scalafix.sbt",
-      """addSbtPlugin("ch.epfl.scala" % "sbt-scalafix" % "0.9.28")"""
+      """addSbtPlugin("ch.epfl.scala" % "sbt-scalafix" % "0.9.29")"""
     )
 
   def scalaStewardScalafixOptions(scalacOptions: List[String]): FileData = {

project/plugins.sbt

@@ -13,4 +13,4 @@ addSbtPlugin("org.portable-scala" % "sbt-scalajs-crossproject" % "1.0.0")
 addSbtPlugin("org.scoverage" % "sbt-scoverage" % "1.8.2")
 
 // This is only here so that Scala Steward updates the version in sbt/package.scala too.
-addSbtPlugin("ch.epfl.scala" % "sbt-scalafix" % "0.9.28")
+addSbtPlugin("ch.epfl.scala" % "sbt-scalafix" % "0.9.29")