solving unweighted hons issue

[VinsRR]

The higher-order networks were unweighted. This snippet:

dag_data = pp.DAGData(pp.IndexMap(list("01234")))
dag_data.append_walk(list("023"), weight=20)
dag_data.append_walk(list("124"), weight=30)

m = pp.MultiOrderModel.from_DAGs(dag_data, max_order=2)

hon_1 = m.layers[1]
hon_2 = m.layers[2]
print(hon_1.data.edge_weight)
print(hon_2.data.edge_weight)

Gives this:

tensor([1., 1., 1., 1.])
tensor([1., 1.])

[M-Lampert]

BTW: This is related to #155

[M-Lampert]

Could be closed due to #173, but best practice would be to merge it into #173 instead to have a clearer/cleaner merge history. @VinsRR can you either close it or merge it?