use Scala 2.13 as default (to avoid problems with scalafix from scala3)

Author: Karry

project/BuildSettings.scala

@@ -31,7 +31,7 @@ object BuildSettings {
     description := "Functional programming toolkit for building server applications in Scala.",
     licenses := Seq("MIT" -> url("https://raw.githubusercontent.com/avast/scala-server-toolkit/master/LICENSE")),
     developers := List(Developer("jakubjanecek", "Jakub Janecek", "[email protected]", url("https://www.avast.com"))),
-    scalaVersion := scala3,
+    scalaVersion := scala213,
     crossScalaVersions := List(scala213, scala212, scala3),
     fork := true,
     libraryDependencies ++= (if (!isScala3(scalaVersion.value)) List(compilerPlugin(Dependencies.kindProjector)) else List.empty) ++ List(