chore: Bump v.kotlin from 1.9.20 to 1.9.21

Bumps `v.kotlin` from 1.9.20 to 1.9.21.

Updates `org.jetbrains.kotlin:kotlin-maven-plugin` from 1.9.20 to 1.9.21

Updates `org.jetbrains.kotlin:kotlin-stdlib` from 1.9.20 to 1.9.21
- [Release notes](https://github.com/JetBrains/kotlin/releases)
- [Changelog](https://github.com/JetBrains/kotlin/blob/master/ChangeLog.md)
- [Commits](JetBrains/kotlin@v1.9.20...v1.9.21)

---
updated-dependencies:
- dependency-name: org.jetbrains.kotlin:kotlin-maven-plugin
  dependency-type: direct:production
  update-type: version-update:semver-patch
- dependency-name: org.jetbrains.kotlin:kotlin-stdlib
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <[email protected]>

pom.xml

@@ -17,7 +17,7 @@
 
     <v.lyo>${project.version}</v.lyo>
 
-    <v.kotlin>1.9.20</v.kotlin>
+    <v.kotlin>1.9.21</v.kotlin>
     <v.dokka>1.9.10</v.dokka>
 
     <v.jersey>2.35</v.jersey>