Bump kotlin.version from 1.8.10 to 1.9.20

Bumps `kotlin.version` from 1.8.10 to 1.9.20.

Updates `org.jetbrains.kotlin:kotlin-bom` from 1.8.10 to 1.9.20
- [Release notes](https://github.com/JetBrains/kotlin/releases)
- [Changelog](https://github.com/JetBrains/kotlin/blob/master/ChangeLog.md)
- [Commits](JetBrains/kotlin@v1.8.10...v1.9.20)

Updates `org.jetbrains.kotlin:kotlin-maven-allopen` from 1.8.10 to 1.9.20

Updates `org.jetbrains.kotlin:kotlin-maven-plugin` from 1.8.10 to 1.9.20

---
updated-dependencies:
- dependency-name: org.jetbrains.kotlin:kotlin-bom
  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-plugin
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

pom.xml

@@ -25,7 +25,7 @@
         <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
         <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
 
-        <kotlin.version>1.8.10</kotlin.version>
+        <kotlin.version>1.9.20</kotlin.version>
         <dokka.version>1.7.20</dokka.version>
 
         <kotlin.compiler.jvmTarget>17</kotlin.compiler.jvmTarget>