Add axis=0 as a default arg for Gather python binding.

python_binding/operator/pybind_Gather.cpp

@@ -24,6 +24,6 @@ void init_Gather(py::module& m) {
     .def("get_outputs_name", &Gather_Op::getOutputsName)
     .def("attributes_name", &Gather_Op::staticGetAttrsName);
     declare_registrable<Gather_Op>(m, "GatherOp");
-    m.def("Gather", &Gather, py::arg("indices"), py::arg("gathered_shape"), py::arg("axis"), py::arg("name") = "");
+    m.def("Gather", &Gather, py::arg("indices"), py::arg("gathered_shape"), py::arg("axis")= 0, py::arg("name") = "");
 }
 }  // namespace Aidge