Bump kotlin-gradle-plugin from 1.5.31 to 1.6.0 (#717)

Bumps [kotlin-gradle-plugin](https://github.com/JetBrains/kotlin) from 1.5.31 to 1.6.0.
- [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)

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

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

Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

build.gradle

@@ -22,7 +22,7 @@ import org.springframework.boot.gradle.plugin.SpringBootPlugin
 
 buildscript {
     ext {
-        kotlin_version = '1.5.31'
+        kotlin_version = '1.6.0'
         spring_boot_version = '2.5.6'
     }