Update plugin org.springframework.boot to v3.4.2

Author: renovate[bot]

Diff for: build.gradle

@@ -22,7 +22,7 @@ plugins {
   id 'jacoco'
   id 'org.owasp.dependencycheck' version '12.0.1'
   id 'org.sonarqube' version '6.0.1.5171'
-  id 'org.springframework.boot' version '3.3.5'
+  id 'org.springframework.boot' version '3.4.2'
   id 'com.github.ben-manes.versions' version '0.52.0'
   id 'hmcts.ccd.sdk' version '5.5.16'
   id 'com.github.hmcts.rse-cft-lib' version '0.19.1561'