Updates runtime (#20)

* Updates scala-exercises runtime library * Updates runtime

Author: juanpedromoreno

build.sbt

@@ -16,7 +16,7 @@ lazy val V = new {
  val collectioncompat: String = "2.1.6"
  val github4s: String = "0.24.1"
  val http4s: String = "0.21.6"
- val runtime: String = "0.6.0"
+ val runtime: String = "0.6.3"
  val scala: String = "2.13.3"
  val scala212: String = "2.12.11"
  val scalacheck: String = "1.14.3"