Update chef repository manager cookbook

This release updates the chef repository manager cookbook to release-0.5.20180828-161555.3c23098. The NXRM version remains unchanged at 3.13.0-01

https://github.com/sonatype/chef-nexus-repository-manager/releases/tag/release-0.5.20180828-161555.3c23098