Migrate tox.ini to extras = xxx instead of deps = .[testing]
This is one instance of swh-environment#2107 (closed)
Test Plan
tox
Migrated from D2318 (view on Phabricator)
Staging instance, all changes can be removed at any time
This is one instance of swh-environment#2107 (closed)
tox
Migrated from D2318 (view on Phabricator)