Bump kotlin.version from 1.6.20 to 1.6.21

Bumps `kotlin.version` from 1.6.20 to 1.6.21.

Updates `kotlin-bom` from 1.6.20 to 1.6.21
- [Release notes](https://github.com/JetBrains/kotlin/releases)
- [Changelog](https://github.com/JetBrains/kotlin/blob/master/ChangeLog.md)
- [Commits](https://github.com/JetBrains/kotlin/commits)

Updates `kotlin-test-junit5` from 1.6.20 to 1.6.21
- [Release notes](https://github.com/JetBrains/kotlin/releases)
- [Changelog](https://github.com/JetBrains/kotlin/blob/master/ChangeLog.md)
- [Commits](https://github.com/JetBrains/kotlin/commits)

Updates `kotlin-maven-allopen` from 1.6.20 to 1.6.21

Updates `kotlin-maven-noarg` from 1.6.20 to 1.6.21

Updates `kotlin-maven-plugin` from 1.6.20 to 1.6.21

---
updated-dependencies:
- dependency-name: org.jetbrains.kotlin:kotlin-bom
  dependency-type: direct:production
  update-type: version-update:semver-patch
- dependency-name: org.jetbrains.kotlin:kotlin-test-junit5
  dependency-type: direct:production
  update-type: version-update:semver-patch
- dependency-name: org.jetbrains.kotlin:kotlin-maven-allopen
  dependency-type: direct:production
  update-type: version-update:semver-patch
- dependency-name: org.jetbrains.kotlin:kotlin-maven-noarg
  dependency-type: direct:production
  update-type: version-update:semver-patch
- dependency-name: org.jetbrains.kotlin:kotlin-maven-plugin
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

pom.xml

@@ -33,7 +33,7 @@
   <properties>
     <axon.version>4.5.9</axon.version>
     <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
-    <kotlin.version>1.6.20</kotlin.version>
+    <kotlin.version>1.6.21</kotlin.version>
     <jackson-kotlin.version>2.13.2</jackson-kotlin.version>
     <kotlin-logging.version>2.1.21</kotlin-logging.version>
     <mockk.version>1.12.3</mockk.version>