Bump org.springframework.boot:spring-boot-gradle-plugin

Bumps [org.springframework.boot:spring-boot-gradle-plugin](https://github.com/spring-projects/spring-boot) from 2.6.7 to 3.1.5.
- [Release notes](https://github.com/spring-projects/spring-boot/releases)
- [Commits](spring-projects/spring-boot@v2.6.7...v3.1.5)

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

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

build.gradle

@@ -7,7 +7,7 @@ buildscript {
     }
     dependencies {
         classpath 'com.netflix.nebula:gradle-extra-configurations-plugin:7.0.0'
-        classpath 'org.springframework.boot:spring-boot-gradle-plugin:2.6.7'
+        classpath 'org.springframework.boot:spring-boot-gradle-plugin:3.1.5'
         classpath 'com.diffplug.spotless:spotless-plugin-gradle:6.+'
     }
 }