Fixed missing input in unit test

aidge_core/unit_tests/test_impl.py

@@ -41,6 +41,7 @@ class test_OperatorImpl(unittest.TestCase):
         generic_matmul_op = matmul.get_operator()
         generic_matmul_op.set_forward_dims(lambda x: x)
         generic_matmul_op.set_impl(testImpl(generic_matmul_op))
+        generic_matmul_op.set_input(0, aidge_core.Tensor(np.arange(18).reshape(1,2,3,3)))
         generic_matmul_op.forward()
         self.assertEqual(GLOBAL_CPT, 1)