Reverse dependencies for weighted_graph

Latest version of the following gems require weighted_graph

Gem	Version	Date	Downloads
dijkstra_graph +5.29 Thousand Downloads	`0.1.1` April 28, 2017	April 28, 2017	5.29 Thousand
adjacency_matrix +3.11 Thousand Downloads	`0.1.0` February 20, 2021	February 20, 2021	3.11 Thousand
floyd_warshall +2.9 Thousand Downloads	`0.1.0` February 20, 2021	February 20, 2021	2.9 Thousand