Fix swh-scanner for python 3.7 and >= 3.8
- Include importlib-metadata in requirements.txt for python 3.7
- Fix swh scanner for python >= 3.8
- Related #3209 (closed)
Migrated from D5551 (view on Phabricator)
Staging instance, all changes can be removed at any time
Migrated from D5551 (view on Phabricator)