Bump org.jetbrains.kotlin.plugin.spring in /examples

Bumps [org.jetbrains.kotlin.plugin.spring](https://github.com/JetBrains/kotlin) from 1.5.21 to 1.8.0.
- [Release notes](https://github.com/JetBrains/kotlin/releases)
- [Changelog](https://github.com/JetBrains/kotlin/blob/master/ChangeLog.md)
- [Commits](JetBrains/kotlin@v1.5.21...v1.8.0)

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

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

Author: dependabot[bot]

examples/spring-boot-kotlin-redis/build.gradle

@@ -1,7 +1,7 @@
 plugins {
     id("org.springframework.boot") version "2.5.2"
     id("org.jetbrains.kotlin.jvm") version "1.5.10"
-    id("org.jetbrains.kotlin.plugin.spring") version "1.5.21"
+    id("org.jetbrains.kotlin.plugin.spring") version "1.8.0"
 }
 
 apply plugin: 'io.spring.dependency-management'