Update kotlin monorepo to v2.3.21

Author: renovate[bot]

gradle/libs.versions.toml

@@ -35,7 +35,7 @@ jsoup = "1.22.2"
 junit-pioneer = "1.9.1"
 junit-platform = "1.14.3"
 junit4 = "4.13.2"
-kotlin = "2.2.21"
+kotlin = "2.3.21"
 ksp = "2.3.6"
 lint-gradle = "1.0.0-alpha05"
 maven-publish = "0.36.0"