Bump kotlinVersion from 1.9.23 to 2.1.0

Bumps `kotlinVersion` from 1.9.23 to 2.1.0.

Updates `jvm` from 1.9.23 to 2.1.0
- [Release notes](https://github.com/JetBrains/kotlin/releases)
- [Changelog](https://github.com/JetBrains/kotlin/blob/v2.1.0/ChangeLog.md)
- [Commits](JetBrains/kotlin@v1.9.23...v2.1.0)

Updates `plugin.spring` from 1.9.23 to 2.1.0
- [Release notes](https://github.com/JetBrains/kotlin/releases)
- [Changelog](https://github.com/JetBrains/kotlin/blob/v2.1.0/ChangeLog.md)
- [Commits](JetBrains/kotlin@v1.9.23...v2.1.0)

---
updated-dependencies:
- dependency-name: jvm
  dependency-type: direct:production
  update-type: version-update:semver-major
- dependency-name: plugin.spring
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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

spring-boot-integration/kotlin-demo-app/build.gradle.kts

@@ -2,7 +2,7 @@ import io.gitlab.arturbosch.detekt.Detekt
 import org.jetbrains.kotlin.gradle.tasks.KotlinCompile
 
 plugins {
-    val kotlinVersion = "1.9.23"
+    val kotlinVersion = "2.1.0"
     kotlin("jvm") version kotlinVersion
     kotlin("plugin.spring") version kotlinVersion
     id("pg-index-health.java-compilation")