chore: Bump the gradle-version-updates group in /backend with 2 updates

Bumps the gradle-version-updates group in /backend with 2 updates: [org.springframework.boot](https://github.com/spring-projects/spring-boot) and org.openrewrite.rewrite.


Updates `org.springframework.boot` from 3.4.0 to 3.4.1
- [Release notes](https://github.com/spring-projects/spring-boot/releases)
- [Commits](spring-projects/spring-boot@v3.4.0...v3.4.1)

Updates `org.openrewrite.rewrite` from 6.28.3 to 6.29.0

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

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

backend/build.gradle

@@ -1,15 +1,15 @@
 plugins {
     id "java"
     id "idea"
-    id "org.springframework.boot" version "3.4.0"
+    id "org.springframework.boot" version "3.4.1"
     id "io.spring.dependency-management" version "1.1.7"
     id "io.freefair.lombok" version "8.11"
     id "com.github.spotbugs" version "6.0.27"
     id "com.github.ben-manes.versions" version "0.51.0"
     id "org.owasp.dependencycheck" version "8.4.3"
     id "com.diffplug.spotless" version "6.25.0"
     id "info.solidsoft.pitest" version "1.15.0"
-    id "org.openrewrite.rewrite" version "6.28.3"
+    id "org.openrewrite.rewrite" version "6.29.0"
 }
 
 spotless {