CI: test_likelihood_ratio_test started failing in macOS tox workflow

[EwoutH]

I just noticed the tox CI workflow is failing on the macOS jobs. It seems like the test_likelihood_ratio_test stopped passing.

• Last passing build: https://github.com/michelbierlaire/biogeme/actions/runs/8779331369
• First failing build: https://github.com/michelbierlaire/biogeme/actions/runs/8874082084

_____________________ TestTools.test_likelihood_ratio_test _____________________
  
  self = <test_tools.TestTools testMethod=test_likelihood_ratio_test>
  
      def test_likelihood_ratio_test(self):
          model1 = (-1340.8, 5)
          model2 = (-1338.49, 7)
          r = biogeme.tools.likelihood_ratio.likelihood_ratio_test(model1, model2)
  >       self.assertSequenceEqual(
              r,
              (
                  'H0 cannot be rejected at level 5.0%',
                  4.6199999999998[91](https://github.com/michelbierlaire/biogeme/actions/runs/8964787830/job/24617129773#step:5:92),
                  5.991464547107979,
              ),
          )
  E       AssertionError: Sequences differ: LRTuple(message='H0 cannot be rejected at[65 chars]0798) != ('H0 cannot be rejected at level 5.0%', 4[31 chars]7[97](https://github.com/michelbierlaire/biogeme/actions/runs/8964787830/job/24617129773#step:5:98)9)
  E       
  E       First differing element 2:
  E       5.991464547107[98](https://github.com/michelbierlaire/biogeme/actions/runs/8964787830/job/24617129773#step:5:99)
  E       5.991464547107979
  E       
  E       - LRTuple(message='H0 cannot be rejected at level 5.0%', statistic=4.61[99](https://github.com/michelbierlaire/biogeme/actions/runs/8964787830/job/24617129773#step:5:100)99999999891, threshold=5.99146454710798)
  E       ? ------- --------                                       ----------                   ----------               ^
  E       
  E       + ('H0 cannot be rejected at level 5.0%', 4.619999999999891, 5.991464547[107](https://github.com/michelbierlaire/biogeme/actions/runs/8964787830/job/24617129773#step:5:108)979)
  E       ?                                                                           ^^
  
  /Users/runner/work/biogeme/biogeme/tests/functions/test_tools.py:131: AssertionError