[docker-py] Fix the type of Model and Collection client attribute

[roberfi]

I see that the type of Model and Collection client attribute is wrong. APIClient is used but it should be DockerClient.

Evidence:

• All Collection objects are initialized with self as client argument in DockerClient class: https://github.com/docker/docker-py/blob/df3f8e2abc5a03de482e37214dddef9e0cee1bb1/docker/client.py#L102C1-L181C45
• Model is then initialized within Collection class using as self.client as the client argument: https://github.com/docker/docker-py/blob/df3f8e2abc5a03de482e37214dddef9e0cee1bb1/docker/models/resource.py#L90C13-L90C80

[github-actions]

According to mypy_primer, this change has no effect on the checked open source code. 🤖🎉

[srittau]

Thanks!