fix mistake

Author: fchapoton

src/sage/combinat/words/finite_word.py

@@ -1684,8 +1684,8 @@ def reduced_rauzy_graph(self, n):
             g.allow_loops(True)
             g.allow_multiple_edges(True)
             for v in l:
-                i = next(g.neighbors_in_iterator(v))
-                o = next(g.neighbors_out_iterator(v))
+                i = next(g.neighbor_in_iterator(v))
+                o = next(g.neighbor_out_iterator(v))
                 g.add_edge(i, o, g.edge_label(i, v)[0] * g.edge_label(v, o)[0])
                 g.delete_vertex(v)
         return g