[Tech] Bump org.springframework.boot:spring-boot-starter-security

Bumps [org.springframework.boot:spring-boot-starter-security](https://github.com/spring-projects/spring-boot) from 3.1.7 to 3.2.4.
- [Release notes](https://github.com/spring-projects/spring-boot/releases)
- [Commits](spring-projects/spring-boot@v3.1.7...v3.2.4)

---
updated-dependencies:
- dependency-name: org.springframework.boot:spring-boot-starter-security
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

backend/build.gradle.kts

@@ -41,7 +41,7 @@ dependencies {
     api("org.springframework.security:spring-security-oauth2-jose:6.1.5")
     api("org.springframework.boot:spring-boot-starter-actuator:3.1.7")
     api("org.springframework.boot:spring-boot-starter-json:3.1.7")
-    api("org.springframework.boot:spring-boot-starter-security:3.1.7")
+    api("org.springframework.boot:spring-boot-starter-security:3.2.4")
     api("org.springframework.boot:spring-boot-starter-data-jpa:3.1.7")
     api("org.springframework.boot:spring-boot-configuration-processor:3.1.7")
     api("org.springframework.boot:spring-boot-starter-cache:3.1.7")