[script.evaluate] Improve exception message

src/ptbench/scripts/evaluate.py

@@ -178,7 +178,7 @@ def evaluate(
         f1_threshold = threshold
         eer_threshold = f1_threshold
     else:
-        raise ValueError("Threshold value is neither an int nor a float")
+        raise ValueError("Threshold value is neither a str or a float")
 
     results_dict = {  # type: ignore
         "pred_data": defaultdict(dict),