Refactor SACConfig properties for improved readability

- Simplified the `image_features` property to directly iterate over `input_features`.
- Removed unused imports and unnecessary code related to main execution, enhancing clarity and maintainability.

lerobot/common/policies/sac/configuration_sac.py

@@ -16,11 +16,10 @@
 # limitations under the License.
 
 from dataclasses import dataclass, field
-from typing import Any, Optional
 
 from lerobot.common.optim.optimizers import MultiAdamConfig
 from lerobot.configs.policies import PreTrainedConfig
-from lerobot.configs.types import NormalizationMode, PolicyFeature, FeatureType
+from lerobot.configs.types import FeatureType, NormalizationMode, PolicyFeature
 
 
 @dataclass
@@ -221,7 +220,7 @@ class SACConfig(PreTrainedConfig):
 
     @property
     def image_features(self) -> list[str]:
-        return [key for key in self.input_features.keys() if "image" in key]
+        return [key for key in self.input_features if "image" in key]
 
     @property
     def observation_delta_indices(self) -> list:
@@ -234,14 +233,3 @@ class SACConfig(PreTrainedConfig):
     @property
     def reward_delta_indices(self) -> None:
         return None
-
-
-if __name__ == "__main__":
-    import draccus
-
-    config = SACConfig()
-    draccus.set_config_type("json")
-    draccus.dump(
-        config=config,
-        stream=open(file="run_config.json", mode="w"),
-    )