package-loaders: Add support for extid versions, and bump it for Debian

The previous commit updated the format of release, and we must not reuse releases created before, hence the bump.

---

Migrated from D6751 (view on Phabricator)

swh/loader/package/archive/tests/test_archive.py

@@ -365,6 +365,7 @@ def test_archive_extid():
         actual_id = p_info.extid(manifest_format=manifest_format)
         assert actual_id == (
             "package-manifest-sha256",
+            0,
             hashlib.sha256(expected_manifest).digest(),
         )