chore: Bump org.springframework.boot

Bumps the gradle-version-updates group in /backend with 1 update: [org.springframework.boot](https://github.com/spring-projects/spring-boot).


Updates `org.springframework.boot` from 3.3.4 to 3.3.5
- [Release notes](https://github.com/spring-projects/spring-boot/releases)
- [Commits](spring-projects/spring-boot@v3.3.4...v3.3.5)

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

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

backend/build.gradle

@@ -1,7 +1,7 @@
 plugins {
     id "java"
     id "idea"
-    id "org.springframework.boot" version "3.3.4"
+    id "org.springframework.boot" version "3.3.5"
     id "io.spring.dependency-management" version "1.1.6"
     id "io.freefair.lombok" version "8.10.2"
     id "com.github.spotbugs" version "6.0.25"