Fail on unmatched ignores

Some times you might have removed a package, or updated without knowing it is in ignores. Would be good if the audit-ci command would fail if such package still exists in the ignores. This would help to keep it in sync with the actual packages & vulnerabilities.

Hi there, thanks for the recommendation.

This was proposed here: #136. Frankly, I am not 100% sure why I closed it since it's a reasonable request.