dictionary changed in data_dir

Taskmaster.py

@@ -174,7 +174,7 @@ class Taskmaster(datasets.GeneratorBasedBuilder):
                 datasets.SplitGenerator(
                     name=challenge_split,
                     gen_kwargs={
-                        "filepath": os.path.join(data_dir, filename),
+                        "filepath": os.path.join(data_dir[challenge_split], filename),
                         "split": challenge_split,
                     },
                 )