Deploy swh.loader.core v2.0.0

Changelog:

• D6396: new Maven loader
• D6750: Updated Debian loader to be able to deal with old origins with md5 manifest
• D6748, D6749, Fix debian hash manifest to use the correct intrinsic version
• D6751: Bump ExtID version for extid entries dsc-sha256

Dev/Ops actions:

• Actually land the related bunch of diffs (see Changelog entry)
• Tag swh.loader.core
• build is fine? [1]
• Actually deploy on workers
• for platform in {staging, production}
  • Restart impacted services:
    • swh-worker@loader_{$pkg_loader} for pkg_loader in {archive,cran,debian,deosit,nixguix,opam,npm,pypi,...}
    • swh-worker@lister
  • Ensure loading is still ok (staging: #3774 (closed), prod: #3774 (closed))

We must use built-in now.

Related to T3770

Impact:

• Schedule back origins with visit_type "deb" (ongoing)

Dependencies pulled:

• swh.model v3.1 (hashes: allowing optional md5 hash computation)
• swh.lister v2.6.1 (debian: improved last_update computations)

Note: v2.0 since it's an api change for the debian loader.

• [1] https://jenkins.softwareheritage.org/job/debian/job/packages/job/DLDBASE/job/gbp-buildpackage/

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Migrated from T3774 (view on Phabricator)