Replace YAML keys from int to str

Replace YAML metadata integer keys with strings, as the Hub does not support integers.
See: https://github.com/huggingface/datasets/issues/5275

README.md

@@ -17,7 +17,6 @@ task_categories:
 - text-classification
 task_ids:
 - sentiment-classification
-paperswithcode_id: null
 pretty_name: ImDB Urdu Reviews
 dataset_info:
   features:
@@ -27,8 +26,8 @@ dataset_info:
     dtype:
       class_label:
         names:
-          0: positive
-          1: negative
+          '0': positive
+          '1': negative
   splits:
   - name: train
     num_bytes: 114670811