Upgrade the minimal version of Eventlet in ``requirements.txt`` files of deliverables using Eventlet. As libraries would be transitioned first, and
as they will have to relies on Asyncio, we would have to always use Eventlet in a compatible version (at least `0.35.0 <https://github.com/eventlet/eventlet/releases/tag/v0.35.0>`_).
So we would have to force this minimal version in all the deliverables that relies on Eventlet.
Acting this way will also avoid pip resolver conflicts related to different versions Eventlet between deliverables. Some deliverables are defining Eventlet in their ``requirements.txt`` some other in their ``test-requirements.txt`` and only for testing purpose. Enforcing the minimal version of Eventlet everywhere would reduce the chances of broken gates and hence, would reduce the pain of the migration.