Update kotlin monorepo to v2.3.21

Author: renovate[bot]

build.sbt

@@ -20,7 +20,7 @@ lazy val V =
     val requests = "0.8.0"
     val minimalMillVersion = "0.10.0"
     val millScipVersion = "0.3.6"
-    val kotlinVersion = "2.2.0"
+    val kotlinVersion = "2.3.21"
     val kotest = "4.6.3"
     val kctfork = "0.7.1"
   }