Bump kotlin.version from 1.8.20 to 1.9.21

Bumps `kotlin.version` from 1.8.20 to 1.9.21.

Updates `org.jetbrains.kotlin:kotlin-stdlib` from 1.8.20 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@v1.8.20...v1.9.21)

Updates `org.jetbrains.kotlin:kotlin-stdlib-jdk8` from 1.8.20 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@v1.8.20...v1.9.21)

Updates `org.jetbrains.kotlin:kotlin-reflect` from 1.8.20 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@v1.8.20...v1.9.21)

Updates `org.jetbrains.kotlin:kotlin-maven-allopen` from 1.8.20 to 1.9.21

Updates `org.jetbrains.kotlin:kotlin-maven-noarg` from 1.8.20 to 1.9.21

Updates `org.jetbrains.kotlin:kotlin-maven-plugin` from 1.8.20 to 1.9.21

---
updated-dependencies:
- dependency-name: org.jetbrains.kotlin:kotlin-stdlib
  dependency-type: direct:production
  update-type: version-update:semver-minor
- dependency-name: org.jetbrains.kotlin:kotlin-stdlib-jdk8
  dependency-type: direct:production
  update-type: version-update:semver-minor
- dependency-name: org.jetbrains.kotlin:kotlin-reflect
  dependency-type: direct:production
  update-type: version-update:semver-minor
- dependency-name: org.jetbrains.kotlin:kotlin-maven-allopen
  dependency-type: direct:production
  update-type: version-update:semver-minor
- dependency-name: org.jetbrains.kotlin:kotlin-maven-noarg
  dependency-type: direct:production
  update-type: version-update:semver-minor
- dependency-name: org.jetbrains.kotlin:kotlin-maven-plugin
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

tracing-axon-example/pom.xml

@@ -31,7 +31,7 @@
 
     <properties>
         <opentracing.version>3.3.1</opentracing.version>
-        <kotlin.version>1.8.20</kotlin.version>
+        <kotlin.version>1.9.21</kotlin.version>
         <kotlin-logging-jvm.version>3.0.5</kotlin-logging-jvm.version>
     </properties>