We use GitLab at work, and I was looking for a way to make deprecation warnings (and other warnings) more visible in the CI status.
One option is to grep through the stderr of your test suite for the word “warning,” and if it is found, exit with some non-zero exit code. GitLab CI lets you mark particular exit codes as allowable failures, so CI will continue, but you get a visual indication that something happened.
GitLab CI also has the ability to display the results of code quality tools, as long as those are given to GitLab in a particular JSON format. I made a simple little package that scans through a log file (from your unit tests or some other Julia workflow), finds all of the warning messages, and writes them out in the required JSON format. GitLab CI then presents them in a very snazzy code quality widget.
I haven’t registered it, but feel free to check out GitLabCodeQualityReports.jl. I also have a test merge request that adds a new warning so you can see what the code quality widget looks like.