1300 Update surragete model test to work with new pyfakefs version (#1301)

Co-authored-by: jubicker <113909589+jubicker@users.noreply.github.com>

Author: xsaschako

pycode/memilio-surrogatemodel/memilio/surrogatemodel_test/test_surrogatemodel_ode_secir_groups.py

@@ -505,9 +505,14 @@ def test_network_fit(self, mock_population, mock_baseline, mock_minimum):
             model.network_fit(
                 path=self.path, model=md,
                 modeltype='classic', training_parameter=training_parameter, filename="data_secir_groups.pickle")
-        error_message = "[Errno 2] No such file or directory in the fake filesystem: '" + \
-            self.path + "data_secir_groups.pickle'"
-        self.assertEqual(str(error.exception), error_message)
+        # check error message
+        error_message_part1 = "[Errno 2] No such file or directory"
+        error_message_part2 = self.path
+        error_message_part3 = "data_secir_groups.pickle"
+
+        self.assertIn(error_message_part1, str(error.exception))
+        self.assertIn(error_message_part2, str(error.exception))
+        self.assertIn(error_message_part3, str(error.exception))
 
         # generate dataset with multiple output
         input_width = 5