fix(deps): update kotlin monorepo to v2

Author: renovate[bot]

Diff for: gradle/libs.versions.toml

@@ -19,7 +19,7 @@ micronaut-logging = "1.3.0"
 # Gradle plugins
 
 micronaut-gradle-plugin = "4.4.4"
-kotlin-gradle-plugin = "1.9.25"
+kotlin-gradle-plugin = "2.0.21"
 ksp-gradle-plugin = "1.9.25-1.0.20"
 
 [libraries]