Fix general type ignore in src

Author: Rocamonde

src/imitation/testing/reward_improvement.py

@@ -45,15 +45,15 @@ def is_significant_reward_improvement(
 
 
 def mean_reward_improved_by(
-    old_rewards: Iterable[float],
-    new_rewards: Iterable[float],
+    old_rews: Iterable[float],
+    new_rews: Iterable[float],
     min_improvement: float,
 ):
     """Checks if mean rewards improved wrt. to old rewards by a certain amount.
 
     Args:
-        old_rewards: Iterable of "old" trajectory rewards (e.g. before training).
-        new_rewards: Iterable of "new" trajectory rewards (e.g. after training).
+        old_rews: Iterable of "old" trajectory rewards (e.g. before training).
+        new_rews: Iterable of "new" trajectory rewards (e.g. after training).
         min_improvement: The minimum amount of improvement that we expect.
 
     Returns:
@@ -66,5 +66,5 @@ def mean_reward_improved_by(
     >>> mean_reward_improved_by([5, 8, 7], [8, 9, 10], 5)
     False
     """
-    improvement = np.mean(new_rewards) - np.mean(old_rewards)  # type: ignore
+    improvement = np.mean(new_rews) - np.mean(old_rews)  # type: ignore[call-overload]
     return improvement >= min_improvement