Bump plugin.spring from 1.9.10 to 2.1.0

Bumps [plugin.spring](https://github.com/JetBrains/kotlin) from 1.9.10 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@v1.9.10...v2.1.0)

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

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

Author: dependabot[bot]

kotlin-wot-integration-tests/build.gradle.kts

@@ -1,5 +1,5 @@
 plugins {
-    kotlin("plugin.spring") version "1.9.10"
+    kotlin("plugin.spring") version "2.1.0"
     id("org.springframework.boot") version "3.1.5" // Use the latest compatible version
     id("io.spring.dependency-management") version "1.1.3"
 }

kotlin-wot-spring-boot-starter/build.gradle.kts

@@ -1,5 +1,5 @@
 plugins {
-    kotlin("plugin.spring") version "1.9.10"
+    kotlin("plugin.spring") version "2.1.0"
     id("org.springframework.boot") version "3.1.5" // Use the latest compatible version
     id("io.spring.dependency-management") version "1.1.3"
 }