chore(deps): bump kotlin.version in /restclient-kotlin-co

Bumps `kotlin.version` from 2.0.21 to 2.1.0.

Updates `org.jetbrains.kotlin:kotlin-test` from 2.0.21 to 2.1.0
- [Release notes](https://github.com/JetBrains/kotlin/releases)
- [Changelog](https://github.com/JetBrains/kotlin/blob/master/ChangeLog.md)
- [Commits](JetBrains/kotlin@v2.0.21...v2.1.0)

Updates `org.jetbrains.kotlin:kotlin-maven-allopen` from 2.0.21 to 2.1.0

Updates `org.jetbrains.kotlin:kotlin-maven-noarg` from 2.0.21 to 2.1.0

Updates `org.jetbrains.kotlin:kotlin-maven-plugin` from 2.0.21 to 2.1.0

---
updated-dependencies:
- dependency-name: org.jetbrains.kotlin:kotlin-test
  dependency-type: direct:development
  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] <support@github.com>

restclient-kotlin-co/pom.xml

@@ -19,7 +19,7 @@
         <maven-failsafe-plugin.version>3.5.2</maven-failsafe-plugin.version>
 
         <!-- kotlin -->
-        <kotlin.version>2.0.21</kotlin.version>
+        <kotlin.version>2.1.0</kotlin.version>
         <kotlin.compiler.incremental>true</kotlin.compiler.incremental>
 
         <!-- dependencies-->