Fix black and flake8 errors.

Author: nadiaya

src/sagemaker/rl/estimator.py

@@ -510,6 +510,9 @@ def default_metric_definitions(cls, toolkit):
                     "Name": "episode_reward_mean",
                     "Regex": "episode_reward_mean: (%s)" % float_regex,
                 },
-                {"Name": "episode_reward_max", "Regex": "episode_reward_max: (%s)" % float_regex, },
+                {
+                    "Name": "episode_reward_max",
+                    "Regex": "episode_reward_max: (%s)" % float_regex,
+                },
             ]
         raise ValueError("An unknown RLToolkit enum was passed in. toolkit: {}".format(toolkit))