Make is_negatively_weighted dispatchable (#7352)

networkx/classes/function.py

@@ -1038,6 +1038,7 @@ def is_weighted(G, edge=None, weight="weight"):
     return all(weight in data for u, v, data in G.edges(data=True))
 
 
+@nx._dispatchable(edge_attrs="weight")
 def is_negatively_weighted(G, edge=None, weight="weight"):
     """Returns True if `G` has negatively weighted edges.