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:
 - token-classification
 task_ids:
 - parsing
-paperswithcode_id: null
 pretty_name: AMTTL
 dataset_info:
   features:
@@ -29,10 +28,10 @@ dataset_info:
     sequence:
       class_label:
         names:
-          0: B
-          1: I
-          2: E
-          3: S
+          '0': B
+          '1': I
+          '2': E
+          '3': S
   config_name: amttl
   splits:
   - name: train