build(deps): bump org.springframework.boot from 4.0.5 to 4.0.6

Bumps org.springframework.boot from 4.0.5 to 4.0.6.

---
updated-dependencies:
- dependency-name: org.springframework.boot
  dependency-version: 4.0.6
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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

Author: dependabot[bot]

gradle/libs.versions.toml

@@ -1,6 +1,6 @@
 [versions]
 java = "21"
-spring-boot = "4.0.5"
+spring-boot = "4.0.6"
 spring-dependency-management = "1.1.7"
 openapi-generator = "7.21.0"
 openapi-tools = "0.2.9"