Check changelog in build tag job
What does this MR do?
Make the "build tag" job fail if the changelog is inconsistent with the git tag.
Why was this MR needed?
To ensure that the changelog is consistent with the git tag.
Does this MR meet the acceptance criteria?
This is backstage really:
Changelog entry added, if necessaryDocumentation created/updatedTests added for this feature/bug
What are the relevant issue numbers?
https://gitlab.com/gitlab-org/security-products/release/issues/50