fixe a bug gathering edges

src/jflow/workflow.py

@@ -283,7 +283,7 @@ class Workflow(threading.Thread):
                 self.__setattr__(param.name, final_vals)
 
     def get_execution_graph(self):
-        graph = Graph()
+        graph = Graph(graph_dict={})
         for cpt in self.components:
             graph.add_vertex(cpt.get_nameid())
             for ioparameter in cpt.__dict__.values():