message: Replace deprecated test_session with cached_session in quantile_ops_test
  This fix replace deprecated test_session with cached_session in
  quantile_ops_test.py to remove warnings during tests
diff: @@ -145,7 +145,7 @@ class QuantileOpsTest(test_util.TensorFlowTestCase):
  save_dir = os.path.join(self.get_temp_dir(), "save_restore")
  save_path = os.path.join(tempfile.mkdtemp(prefix=save_dir), "hash")
  - with self.test_session() as sess:
  + with self.cached_session() as sess:
  accumulator = boosted_trees_ops.QuantileAccumulator(
  num_streams=2, num_quantiles=3, epsilon=self.eps, name="q0")
  @@ -177,7 +177,7 @@ class QuantileOpsTest(test_util.TensorFlowTestCase):
  save_dir = os.path.join(self.get_temp_dir(), "save_restore")
  save_path = os.path.join(tempfile.mkdtemp(prefix=save_dir), "hash")
  - with self.test_session() as sess:
  + with self.cached_session() as sess:
  accumulator = boosted_trees_ops.QuantileAccumulator(
  num_streams=2, num_quantiles=3, epsilon=self.eps, name="q0")
  