You are using a deprecated resolve URL for Pentaho projects. The correct resolve URL is:
https://nexus.pentaho.org/content/groups/omni
Please refer to the official Pentaho Documentation on how to build Pentaho projects with Maven:
https://github.com/pentaho/maven-parent-poms/wiki
This is a sample settings.xml file that could be used in your local build environment:
https://github.com/pentaho/maven-parent-poms/blob/master/maven-support-files/settings.xml