fix pylint

tests/ut/python/dataset/test_graphdata.py

@@ -22,7 +22,7 @@ DATASET_FILE = "../data/mindrecord/testGraphData/testdata"
 def test_graphdata_getfullneighbor():
     g = ds.GraphData(DATASET_FILE, 2)
     nodes = g.get_all_nodes(1)
-    assert len(nodes) is 10
+    assert len(nodes) == 10
     nodes_list = nodes.tolist()
     neighbor = g.get_all_neighbors(nodes_list, 2)
     assert neighbor.shape == (10, 6)