chore(gripper): backward compatibility non list action

Author: juelg

python/rcs/envs/base.py

@@ -724,6 +724,9 @@ def action(self, action: dict[str, Any]) -> dict[str, Any]:
         action = copy.deepcopy(action)
         assert self.gripper_key in action, "Gripper action not found."
 
+        if isinstance(gripper_action, int) or isinstance(gripper_action, float):
+            gripper_action = [gripper_action]  # type: ignore
+
         gripper_action = np.round(action[self.gripper_key]) if self.binary else action[self.gripper_key]
         gripper_action = np.clip(gripper_action, 0.0, 1.0)