Bump org.springframework.boot in /spring-boot-reactive

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]>

spring-boot-reactive/build.gradle

@@ -1,5 +1,5 @@
 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 'java'
     id("com.google.cloud.tools.jib") version "3.4.0"