Crates.io: Add last_update for each version of a crate
In order to reduce http api call amount made by the loader, download a crates.io database dump, and parse its csv files to get a last_update value for each versions of a Crate. Those values are sent to the loader through extra_loader_arguments 'crates_metadata'.
'artifacts' and 'crates_metadata' now uses "version" as key.
Related T4104, swh-loader-core!427 (closed)
Migrated from D8454 (view on Phabricator)