Fix formatting

Author: larissapoghosyan

pydatastructs/graphs/tests/test_adjacency_matrix.py

@@ -49,4 +49,4 @@ def test_AdjacencyMatrix():
     g.remove_vertex(3)
     neighbors = g.neighbors(2)
     assert neighbors == [v_0]
-    assert g.num_vertices() == 3
+    assert g.num_vertices() == 3