chore(core-deps): update dependency org.jetbrains.kotlin:kotlin-stdlib to v2.3.21

Author: renovate[bot]

gradle/libs.versions.toml

@@ -1,7 +1,7 @@
 [versions]
 alchemist = "42.3.35"
 kotest = "5.9.1"
-kotlin = "2.2.0"
+kotlin = "2.3.21"
 mockito = "5.18.0"
 
 [libraries]