Bump org.springframework.boot from 3.4.1 to 3.4.2 in /submissions

Bumps [org.springframework.boot](https://github.com/spring-projects/spring-boot) from 3.4.1 to 3.4.2.
- [Release notes](https://github.com/spring-projects/spring-boot/releases)
- [Commits](spring-projects/spring-boot@v3.4.1...v3.4.2)

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

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

submissions/build.gradle.kts

@@ -1,7 +1,7 @@
 apply(from = rootProject.file("buildSrc/shared.gradle.kts"))
 
 plugins {
-    id("org.springframework.boot") version "3.4.1"
+    id("org.springframework.boot") version "3.4.2"
     id("io.spring.dependency-management") version "1.1.7"
     id("reportstream.project-conventions")
     kotlin("plugin.spring") version "2.1.0"