Update dependency org.jetbrains.kotlin:kotlin-gradle-plugin to v2.2.21

Author: renovate[bot]

gradle/libs.versions.toml

@@ -22,7 +22,7 @@ hilt = "2.57.2"
 junit4 = "4.13.2"
 jupiter = "5.13.4"
 kotest = "6.0.3"
-kotlin = "2.2.20"
+kotlin = "2.2.21"
 ksp = "2.2.20-2.0.4"
 material3 = "1.13.0"
 mockk = "1.14.6"