update scala

Author: rmgk

project/Settings.scala

@@ -8,7 +8,7 @@ import sbt.Keys.*
 object Settings {
 
   // also consider updating the -source param below
-  val scala3VersionString = sys.env.getOrElse("SCALA_VERSION", "3.6.3")
+  val scala3VersionString = sys.env.getOrElse("SCALA_VERSION", "3.6.4")
 
   // needs either 3.7 or 3.5 minor version in 3.6, otherwise there is a unfixable warning about changed implicit order
   // see https://github.com/scala/scala3/issues/22153