Bump spring.boot.version from 2.7.14 to 2.7.15

Bumps `spring.boot.version` from 2.7.14 to 2.7.15.

Updates `org.springframework.boot:spring-boot-starter` from 2.7.14 to 2.7.15
- [Release notes](https://github.com/spring-projects/spring-boot/releases)
- [Commits](spring-projects/spring-boot@v2.7.14...v2.7.15)

Updates `org.springframework.boot:spring-boot-maven-plugin` from 2.7.14 to 2.7.15
- [Release notes](https://github.com/spring-projects/spring-boot/releases)
- [Commits](spring-projects/spring-boot@v2.7.14...v2.7.15)

Updates `org.springframework.boot:spring-boot-dependencies` from 2.7.14 to 2.7.15
- [Release notes](https://github.com/spring-projects/spring-boot/releases)
- [Commits](spring-projects/spring-boot@v2.7.14...v2.7.15)

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

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

pom.xml

@@ -42,7 +42,7 @@ limitations under the License.
 		<log4j.version>2.20.0</log4j.version>
 
 		<spring.version>5.3.29</spring.version>
-		<spring.boot.version>2.7.14</spring.boot.version>
+		<spring.boot.version>3.1.3</spring.boot.version>
 		<!--
 		DKF: if you update spring.boot.version, also update the annotation
 		  processor binding in Eclipse for SpiNNaker-allocserv: