Update kotlin monorepo to v2.0.21

Signed-off-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>

build.gradle

@@ -20,7 +20,7 @@ buildscript {
         documentScannerVersion = "1.1.1"
         espressoVersion = "3.6.1"
         jacoco_version = '0.8.12'
-        kotlin_version = '2.0.20'
+        kotlin_version = '2.0.21'
         markwonVersion = "4.6.2"
         mockitoVersion = "4.11.0"
         mockitoKotlinVersion = "4.1.0"