Warning message in test

[inakleinbottle]

The following warning message is displayed when running the test suite for esig:

esig/tests/test_package.py::TestESIG::test_chen
  /home/sam/datasig/esig/esig/tests/test_package.py:145: VisibleDeprecationWarning: Creating an ndarray from ragged nested sequences (which is a list-or-tuple of lists-or-tuples-or ndarrays with different lengths or shapes) is deprecated. If you meant to do this, you must specify 'dtype=object' when creating the ndarray
    self.assertEqual(all(np.concatenate((np.array(chen)-np.array(sig_concat)).flatten())),0)

-- Docs: https://docs.pytest.org/en/stable/warnings.html

This is caused by the statement in the assert to check if the two arrays are equal.

Numpy actually provides a testing interface that we should probably use instead (https://numpy.org/doc/stable/reference/routines.testing.html).