pytest and pytest-asyncio should not be regular dependencies #143

Currently, this package requires pytest and pytest-asyncio. This causes them to be included in production deployments. These two testing packages should only be dependencies for testing. I'm not a Python expert so I don't know the best way to set that up. It sounds like it might be sufficient to move them to test extras or dev dependencies. If that doesn't suit this package, it might be necessary to split it into two packages fdk and fdk-testing.