quimb test is broken

[dlyongemallo]

With the package quimb (e.g., version 1.7.3) installed , running runtests.sh results in the following failure:

======================================================================
ERROR: tests.test_quimb (unittest.loader._FailedTest)
----------------------------------------------------------------------
ImportError: Failed to import test module: tests.test_quimb
Traceback (most recent call last):
  File "/usr/lib/python3.10/unittest/loader.py", line 436, in _find_test_path
    module = self._get_module_from_name(name)
  File "/usr/lib/python3.10/unittest/loader.py", line 377, in _get_module_from_name
    __import__(name)
  File "/home/davinci/workspace/pyzx/tests/test_quimb.py", line 39, in <module>
    import quimb as qu
  File "/home/davinci/workspace/pyzx/.venv/lib/python3.10/site-packages/quimb/__init__.py", line 26, in <module>
    from .core import (
  File "/home/davinci/workspace/pyzx/.venv/lib/python3.10/site-packages/quimb/core.py", line 2186, in <module>
    sp.csr_matrix._mul_vector = csr_mulvec_wrap(sp.csr_matrix._mul_vector)
AttributeError: type object 'csr_matrix' has no attribute '_mul_vector'. Did you mean: '_matmul_vector'?

(The quimb package is not installed in the CI/CD workflow on GitHub, so this test is never run.)