[Tech] Bump org.springframework.boot from 3.2.0 to 3.2.2 in /backend

Bumps [org.springframework.boot](https://github.com/spring-projects/spring-boot) from 3.2.0 to 3.2.2.
- [Release notes](https://github.com/spring-projects/spring-boot/releases)
- [Commits](spring-projects/spring-boot@v3.2.0...v3.2.2)

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

Signed-off-by: dependabot[bot] <support@github.com>

backend/build.gradle.kts

@@ -1,7 +1,7 @@
 plugins {
     `java-library`
     `maven-publish`
-    id("org.springframework.boot") version "3.2.0"
+    id("org.springframework.boot") version "3.2.2"
     id("org.jetbrains.kotlin.plugin.spring") version "1.9.10"
     kotlin("jvm") version "1.9.10"
     id("org.jetbrains.kotlin.plugin.allopen") version "1.9.10"