remove unused type alias

src/lerobot/rl/data_sources/data_mixer.py

@@ -15,12 +15,10 @@
 from __future__ import annotations
 
 import abc
-from typing import Any
 
+from lerobot.rl.algorithms.base import BatchType
 from lerobot.rl.buffer import ReplayBuffer, concatenate_batch_transitions
 
-BatchType = dict[str, Any]
-
 
 class DataMixer(abc.ABC):
     """Abstract interface for all data mixing strategies.