Jkube: Update Spring Boot Quickstarts to latest version

[rohanKanojia]

Our Spring Boot Quickstarts are based upon spring boot versions that were released a year ago. We need to update them to the latest version of spring boot.

1. Update Spring Boot version in Quickstart to latest version
2. Check if Quickstart is building fine after version bump
3. Test if upgraded quickstart is working okay with jkube. Check mvn k8s:build, mvn k8s:resource, mvn k8s:apply goals with a local Kubernetes cluster(minikube/kind)

https://github.com/eclipse/jkube/tree/master/quickstarts/maven/spring-boot
https://github.com/eclipse/jkube/tree/master/quickstarts/maven/spring-boot-crd
https://github.com/eclipse/jkube/tree/master/quickstarts/maven/spring-boot-camel-complete
https://github.com/eclipse/jkube/tree/master/quickstarts/maven/spring-boot-dekorate
https://github.com/eclipse/jkube/tree/master/quickstarts/maven/spring-boot-with-jib
https://github.com/eclipse/jkube/tree/master/quickstarts/maven/spring-boot-watch

[manusa]

It would also be necessary to check the update works with OpenShift in those quickstarts where it's applicable.

[rohanKanojia]

In case testing on OpenShift is needed, use Red Hat Developer Sandbox[0]

[0] https://developers.redhat.com/developer-sandbox

[rohanKanojia]

@theexplorist : Please review if the issue description is clear enough. If it looks okay to you and you're interested in working on this, I'll assign it to you.

[theexplorist]

@rohanKanojia Assign me this issue!

[theexplorist]

Testing the build, will be submitting PR!