[export_cpp] test_export broken: operator output/output is a list

hello,

I don't know if something changed for operators, but now test_export is broken because operator.get_input(0) andoperator.get_output(0) return lists.

I just pulled last dev version and tried to run test_export.py

Thanks,

Bottom of the error log :

  File "/home/share/360-Architecture_Conception_Logiciel/360.1-Projets/360.1.13-AD_POC/Code/aidge/aidge/aidge_export_cpp/aidge_export_cpp/unit_tests/test_export.py", line 127, in unit_test_export
    tensor = aidge_core.Tensor(_np_init(value.dims()))
                                        ^^^^^^^^^^^^
TypeError: 'list' object is not callable

----------------------------------------------------------------------
Ran 86 tests in 15.292s

FAILED (errors=72, expected failures=1)