fixing global_idx to update on each yield

BabyLM.py

@@ -107,4 +107,5 @@ class BabyLM(datasets.GeneratorBasedBuilder):
         for filepath in filepaths:
             with open(filepath, encoding="utf-8") as f:
                 for row in f:
-                    yield global_idx, {"text": row}
+                    yield global_idx, {"text": row}
+                    global_idx += 1