Django model utils issue on devstack

[OmarIthawi]

Problem: Devstack breaks and throws a TypeError error on the LMS.

django-tiers 0.2.1 requires django-model-utils<=2.3.1, but you'll have django-model-utils 3.2.0 which is incompatible.

See the LMS pages show TypeError exception error instructions.

[OmarIthawi]

Now pip gives me this on AMC pip install -r requirements/base.txt.

ERROR: After October 2020 you may experience errors when installing or updating packages. This is because pip will change the way that it resolves dependency conflicts.
We recommend you use --use-feature=2020-resolver to test your packages with the new resolver before it becomes the default.
django-tiers 0.2.1 requires django-model-utils<=2.3.1, but you'll have django-model-utils 3.2.0 which is incompatible. 

[thraxil]

I think the django-models-utils<=2.3.1 constraint in django-tiers isn't necessary. It looks like it was added in the initial commit: https://github.com/appsembler/django-tiers/blame/master/setup.py#L26 and has never been updated. django-tiers only uses the TimeStampedModel from django-model-utils and that shouldn't require any kind of version restriction. I can only assume that the contstraint was originally placed as boilerplate.

[OmarIthawi]

Thanks @thraxil! I'll just remove the constraint then, it should fix this devstack issue.