Recent migration from the scrubber which did not comply full with the documentation  in
regards to migration started some work to fix it  It fixed the migration for the
scrubber but broke some other modules by mistake.
After further discussion with @douardda, we've come to a plan to properly fix everything.
- Keep the current core code 
- Fix swh.storage's datastore to add the attribute current_version
- Fix swh.indexer's storage datastore to add the attribute current version
- Drop  which is ok providing ^ and  which is totally irrelevant