Show more detailed error message for failing Maven upload

[adinauer]

Release failed to deploy to Maven / Nexus (https://github.com/getsentry/publish/actions/runs/5069891357/jobs/9104136850) due to missing elements on pom.xml.

While it's possible to view details about the error on the Nexus Web UI it'd be a lot easier to show them in the publish log. Not sure if a description is returned when the API call fails. It tries to upload for a while then at some point reports a 502 HTTP error.