Pytest can't collect TestWeights

[NicolasHug]

test/test_prototype_models.py:175
  /fsx/users/nicolashug/work/vision/test/test_prototype_models.py:175: PytestCollectionWarning: cannot collect test class 'TestWeights' because it has a __init__ constructor (from: test/test_prototype_models.py::TestHandleLegacyInterface)
    class TestWeights(WeightsEnum):

I think we just need to rename TestWeights into something that doesn't start with Test so that pytest doesn't mistake it for a test class

CC @pmeier

cc @pmeier