Remove unused functions and imports from modeling_sac.py

- Deleted the `find_and_copy_params` function and the `Ensemble` class, as they were deemed unnecessary.
- Cleaned up imports by removing `from_modules` from `tensordict` to enhance code clarity.
- Simplified the assertion in the `Policy` class for better readability.

pyproject.toml

@@ -91,7 +91,7 @@ dynamixel = ["dynamixel-sdk", "pynput"]
 feetech = ["feetech-servo-sdk", "pynput"]
 intelrealsense = ["pyrealsense2"]
 stretch = ["hello-robot-stretch-body", "pyrender", "pyrealsense2", "pynput"]
-hilserl = ["transformers", "torchmetrics", "grpcio", "protobuf", "tensordict"]
+hilserl = ["transformers", "torchmetrics", "grpcio", "protobuf"]
 mani_skill = ["mani-skill"]
 
 [tool.ruff]