`pytest_lazyfixture` incompatible with `pytest_cases`

[jklaise]

Attempting to run alibi tests with pytest_cases installed throws an error about an unusued fixture. Uninstalling pytest_cases makes the tests pass.

Since we're using pytest_cases for testing alibi-detect it would be worth investigating how to make the two dev environments compatible. One option could be to move alibi usage of pytest_lazyfixture to pytest_cases. @ascillitoe