Upgrade Quarkus

Based on a Quarkus project, newly generated with:

 mvn io.quarkus.platform:quarkus-maven-plugin:2.5.2.Final:create -DprojectGroupId=theodolite -DprojectArtifactId=theodolite -DclassName="org.acme.rest.GreetingResource" -Dpath="/theodolite" -Dextensions="kotlin,kubernetes-client" -DbuildTool=gradle

To Do:

• Check if paths in README are still valid

Will fix #215 (closed).