`go-kit/kit/log` was deprecated and generating warnings
# Checklist for submitter
If some of the following don't apply, delete the relevant line.
<!-- Note that API documentation changes are now addressed by the
product design team. -->
- [x] Manual QA for all new/changed functionality
This only applies to Premium users, we want to show the vulnerabilities' published date anywhere vulnerabilities are shown including API endpoints and third party integrations.
* add premium feature critical policies
* update documentation
* add test for premium-only field
* update old change-file
* test policies more comprehensively
* also test team policies
* PATCH returns wrong timestamp, updating test
