Update to Spring Boot 4.0.0

[bmatthews68]

Please consider upgrading to Spring Boot 4.0.0.

Simply updating the Spring Boot BOM version is not sufficient due to the following issues:

• Spring Boot 4 switched to using Jackson 3 by default while Fabric 8 Kubernetes client uses Jackson 2
• Some classes by the health indicator and tests have moved to new packages and jar files

I already submitted a PR for this -> #266

[csviri]

Upgraded, and created a release! thank you @bmatthews68 !