Update zio to 2.0.15 (#579)

build.sbt

@@ -11,7 +11,7 @@ val versionOf = new {
   val log4s         = "1.10.0"
   val scalaCheck    = "1.17.0"
   val scalaTest     = "3.2.16"
-  val zio           = "2.0.14"
+  val zio           = "2.0.15"
   val scribe        = "3.11.5"
 }