[examples/text-classification] Fix a bug for using one's own dataset of a regression task (#9411)

examples/text-classification/run_glue.py

@@ -289,7 +289,7 @@ def main():
                 f"model labels: {list(sorted(label_name_to_id.keys()))}, dataset labels: {list(sorted(label_list))}."
                 "\nIgnoring the model labels as a result.",
             )
-    elif data_args.task_name is None:
+    elif data_args.task_name is None and not is_regression:
         label_to_id = {v: i for i, v in enumerate(label_list)}
 
     def preprocess_function(examples):