Add missing uniqueness spec for Mdm::Module::Relationship
Add missing uniqueness spec for Mdm::Module::Relationship

[#50752269]

rapid7/metasploit-model,rapid7/metasploit-model,rapid7/metasploit-cache,rapid7/metasploit-cache,farias-r7/metasploit_data_models,rapid7/metasploit-cache,bcook-r7/metasploit_data_models,farias-r7/metasploit_data_models,bcook-r7/metasploit_data_models,bcook-r7/metasploit_data_models,farias-r7/metasploit_data_models,rapid7/metasploit-model,rapid7/metasploit-cache,rapid7/metasploit_data_models,rapid7/metasploit_data_models,rapid7/metasploit_data_models