Fixed tests for cpu only platforms

[galqiwi]

test_4bit_warnings is the only test that fails on cpu only platforms with CUDA-enabled torch.

The reason for this is that other tests fall into this branch

except RuntimeError as re:
    # CUDA-enabled Torch build, but no CUDA-capable device found
    if "Found no NVIDIA driver on your system" in str(re):
        pytest.skip("No NVIDIA driver found")
    raise

While test_4bit_warnings fails with Failed: DID NOT WARN. No warnings of type (<class 'UserWarning'>,) were emitted, as the error is catched by pytest.warns.

[galqiwi]

Sorry, overlooked 3 tests that fail during setup in linear8bit fixture.

Now pytest ./tests truly works

Results (295.12s (0:04:55)):
      54 passed
    3209 skipped

[Titus-von-Koeller]

Thank you so much @galqiwi, really appreciated! It's always good to have folks with a hands-on attitude and spot-on :)

Sorry for the delay, unfortunately was out sick, etc..