python-lal test suite fails on Python 3.13

The test suite for python-lal 3.13 is failing because unittest.makeSuite was removed, from the build log:

Traceback (most recent call last):
  File "/builds/lscsoft/lalsuite/lal/test/python/utils_cache_verify.py", line 32, in <module>
    suite.addTest(unittest.makeSuite(test_docstrings))
                  ^^^^^^^^^^^^^^^^^^

This function was deprecated in Python 3.11 to be removed in Python 3.13, see https://docs.python.org/3.11/whatsnew/3.11.html.