Bump org.springframework.boot from 2.7.18 to 3.4.3

Bumps [org.springframework.boot](https://github.com/spring-projects/spring-boot) from 2.7.18 to 3.4.3.
- [Release notes](https://github.com/spring-projects/spring-boot/releases)
- [Commits](spring-projects/spring-boot@v2.7.18...v3.4.3)

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

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

Author: dependabot[bot]

spring-boot-2-demo-app/build.gradle.kts

@@ -2,7 +2,7 @@ plugins {
     id("sb-ot-demo.java-conventions")
     id("sb-ot-demo.forbidden-apis")
     id("sb-ot-demo.docker")
-    id("org.springframework.boot") version "2.7.18"
+    id("org.springframework.boot") version "3.4.3"
     id("io.freefair.lombok")
 }