Compare proposed release performance with previous release #2387
Description
Currently the performance benchmark suite only runs in CI on pushes and pull requests. On pushes, the performance of HEAD~ is compared with origin/HEAD; and on pull request, the tip of the pull request is compared with the branch it is to be merged into.
We should also have benchcomp running the performance regression suite before a release, or as a result of pushing a tag. This would compare the release against the previous release.