Make Scala 3 the default target

That way the default will always be the latest released version of
Scala.

Author: smarter

api/src/main/scala/com.olegych.scastie.api/Inputs.scala

@@ -22,7 +22,7 @@ object Inputs {
   def default: Inputs = Inputs(
     _isWorksheetMode = true,
     code = defaultCode,
-    target = ScalaTarget.Jvm.default,
+    target = ScalaTarget.Scala3.default,
     libraries = Set(),
     librariesFromList = List(),
     sbtConfigExtra = """|scalacOptions ++= Seq(

sbt-runner/src/test/scala/com.olegych.scastie.sbt/SbtActorTest.scala

@@ -107,7 +107,7 @@ class SbtActorTest() extends TestKit(ActorSystem("SbtActorTest")) with ImplicitS
     val message = "No Predef!"
     val input = Inputs.default.copy(
       sbtConfigExtra = "scalacOptions += \"-Yno-predef\" ",
-      code = s"""scala.Predef.println("$message")"""
+      code = s"""@main def Test = scala.Predef.println("$message")"""
     )
 //    run(input)(_ => true)
 //    run(input.copy(sbtConfigExtra = input.sbtConfigExtra + "\nname := \"aaa\" "))(_ => true)
@@ -152,7 +152,7 @@ class SbtActorTest() extends TestKit(ActorSystem("SbtActorTest")) with ImplicitS
 
   test("no warnings by default") {
     val scala =
-      Inputs.default.copy(code = "println(1 + 1)", sbtConfigExtra = """scalacOptions ++= List("-Xlint", "-Xfatal-warnings")""")
+      Inputs.default.copy(code = "println(1 + 1)", sbtConfigExtra = """scalacOptions ++= List("-Xfatal-warnings")""")
     run(scala)(assertUserOutput("2"))
   }