I have not been able to find a working trinity repository for opensuse 42.3. I had been using the mirror https://build.opensuse.org/project/show/home:PunisherHD:Trinity:stable previously, but that appears to be unmaintained and is unbuilt for 42.3. All opensuse versions of the trinitydesktop.org mirror error that repomd.xml is not digitally signed and I have imported the GPG key.