fix robosuite example

Author: Tavish9

tensorflow_datasets/rlds/datasets/robosuite_panda_pick_place_can/robosuite_panda_pick_place_can.py

@@ -186,9 +186,11 @@ class RobosuitePandaPickPlaceCan(tfds.core.GeneratorBasedBuilder):
           reward_info=np.float64,
           discount_info=np.float64,
           episode_metadata_info={
-              'agent_id': np.str_,
-              'episode_index': np.int32,
-              'episode_id': np.str_,
+              'episode_metadata': {
+                'agent_id': np.str_,
+                'episode_index': np.int32,
+                'episode_id': np.str_,
+              },
           },
           step_metadata_info={
               'tag:placed': np.bool_,