Update pom.xml

[WARNING] 
[WARNING] Some problems were encountered while building the effective model for de.holisticon.maven:holisticon-oss-parent:pom:2-SNAPSHOT
[WARNING] The expression ${artifactId} is deprecated. Please use ${project.artifactId} instead.
[WARNING] The expression ${version} is deprecated. Please use ${project.version} instead.
[WARNING] 
[WARNING] It is highly recommended to fix these problems because they threaten the stability of your build.
[WARNING] 
[WARNING] For this reason, future Maven versions might no longer support building such malformed projects.
[WARNING]