Switch default source version to 3.6

Author: hamzaremmal

compiler/src/dotty/tools/dotc/config/SourceVersion.scala

@@ -28,7 +28,7 @@ enum SourceVersion:
   def isAtMost(v: SourceVersion) = stable.ordinal <= v.ordinal
 
 object SourceVersion extends Property.Key[SourceVersion]:
-  def defaultSourceVersion = `3.5`
+  def defaultSourceVersion = `3.6`
 
   /** language versions that may appear in a language import, are deprecated, but not removed from the standard library. */
   val illegalSourceVersionNames = List("3.1-migration").map(_.toTermName)