drop plugin changes for scalac 3.4

Author: Oron Port

build.sbt

@@ -52,26 +52,12 @@ lazy val internals = project
     libraryDependencies ++= commonDependencies
   )
 
-def additionalSources(scalaVersion: String, base: File): Seq[File] = {
-  CrossVersion.partialVersion(scalaVersion) match {
-    case Some((3, minor)) if minor <= 4 =>
-      Seq(base / "src" / "main" / "scala-3.4-")
-    case Some((3, minor)) if minor >= 5 =>
-      Seq(base / "src" / "main" / "scala-3.5+")
-    case _ =>
-      Seq.empty
-  }
-}
 lazy val plugin = project
   .settings(
     name := s"$projectName-plugin",
     settings,
     crossTarget := target.value / s"scala-${scalaVersion.value}", // workaround for https://github.com/sbt/sbt/issues/5097
     crossVersion := CrossVersion.full,
-    Compile / unmanagedSourceDirectories ++= {
-      val base = baseDirectory.value
-      additionalSources(scalaVersion.value, base)
-    },
     libraryDependencies += "org.scala-lang" %% "scala3-compiler" % compilerVersion % "provided"
   ).dependsOn(internals)