fix pusht images type from float32 to uint8, update gym-pusht dependencies

lerobot/common/datasets/pusht.py

@@ -145,6 +145,9 @@ class PushtDataset(torch.utils.data.Dataset):
             assert (episode_ids[idx0:idx1] == episode_id).all()
 
             image = imgs[idx0:idx1]
+            assert image.min() >= 0.0
+            assert image.max() <= 255.0
+            image = image.type(torch.uint8)
 
             state = states[idx0:idx1]
             agent_pos = state[:, :2]