fix(deps): bump spring-boot to 4.0.7 for patched Spring Framework 7.0.8 (GHSA-x23c-287f-qqv5)

Spring Boot 4.0.6 manages Spring Framework 7.0.7, which is vulnerable to a
Denial of Service issue in versioned resource handling in Spring MVC and
WebFlux (GHSA-x23c-287f-qqv5, Dependabot alerts #119 and #120). Spring Boot
4.0.7 upgrades the managed Spring Framework version to the patched 7.0.8.

Co-Authored-By: Catarina Pinheiro Correia <catarina.correia@getyourguide.com>

Author: claude

gradle/libs.versions.toml

@@ -1,6 +1,6 @@
 [versions]
 java = "21"
-spring-boot = "4.0.6"
+spring-boot = "4.0.7"
 spring-dependency-management = "1.1.7"
 openapi-generator = "7.21.0"
 openapi-tools = "0.2.9"