build(deps): bump org.springframework.boot in /11_flow/server

Bumps [org.springframework.boot](https://github.com/spring-projects/spring-boot) from 3.3.5 to 3.4.0.
- [Release notes](https://github.com/spring-projects/spring-boot/releases)
- [Commits](spring-projects/spring-boot@v3.3.5...v3.4.0)

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

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

11_flow/server/build.gradle.kts

@@ -1,7 +1,7 @@
 import org.jetbrains.kotlin.gradle.tasks.KotlinCompile
 
 plugins {
-    id("org.springframework.boot") version "3.3.5"
+    id("org.springframework.boot") version "3.4.0"
     id("io.spring.dependency-management") version "1.1.6"
     id("org.jetbrains.kotlin.plugin.jpa") version "2.0.21"
     kotlin("jvm") version "2.0.21"