Update kotlin monorepo to v2.2.21 (#58)

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

Author: renovate[bot]

pom.xml

@@ -12,7 +12,7 @@
 
     <properties>
         <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
-        <kotlin.version>2.2.20</kotlin.version>
+        <kotlin.version>2.2.21</kotlin.version>
         <junit.version>4.13.2</junit.version>
         <sonar.projectKey>piomin_sample-kotlin-playground</sonar.projectKey>
         <sonar.organization>piomin</sonar.organization>