Bump org.springframework.boot in /whiskers-cloudnative

Bumps [org.springframework.boot](https://github.com/spring-projects/spring-boot) from 3.1.4 to 3.1.5.
- [Release notes](https://github.com/spring-projects/spring-boot/releases)
- [Commits](spring-projects/spring-boot@v3.1.4...v3.1.5)

---
updated-dependencies:
- dependency-name: org.springframework.boot
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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

whiskers-cloudnative/build.gradle.kts

@@ -2,7 +2,7 @@ import org.jetbrains.kotlin.gradle.tasks.KotlinCompile
 import org.springframework.boot.gradle.tasks.bundling.BootBuildImage
 
 plugins {
-	id("org.springframework.boot") version "3.1.4"
+	id("org.springframework.boot") version "3.1.5"
 	id("io.spring.dependency-management") version "1.1.3"
 //	id("org.springframework.experimental.aot") version "0.12.1"
 	id("org.graalvm.buildtools.native") version "0.9.27"