Bump kotlin.version from 1.8.10 to 1.8.20

Bumps `kotlin.version` from 1.8.10 to 1.8.20.

Updates `kotlin-stdlib` from 1.8.10 to 1.8.20
- [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-junit` from 1.8.10 to 1.8.20
- [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-plugin` from 1.8.10 to 1.8.20

---
updated-dependencies:
- dependency-name: org.jetbrains.kotlin:kotlin-stdlib
  dependency-type: direct:production
  update-type: version-update:semver-patch
- dependency-name: org.jetbrains.kotlin:kotlin-test-junit
  dependency-type: direct:development
  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>

rxjava2-jdbc-kotlin-example/pom.xml

@@ -13,7 +13,7 @@
     <description>RxJava2 streams for jdbc</description>
     <packaging>pom</packaging>
     <properties>
-        <kotlin.version>1.8.10</kotlin.version>
+        <kotlin.version>1.8.20</kotlin.version>
     </properties>
     <dependencies>
         <dependency>