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

@@ -35,9 +35,9 @@ dataset_info:
     dtype:
       class_label:
         names:
-          0: AGAINST
-          1: FAVOR
-          2: NEUTRAL
+          '0': AGAINST
+          '1': FAVOR
+          '2': NEUTRAL
   splits:
   - name: train
     num_bytes: 1406250
@@ -60,9 +60,9 @@ dataset_info:
     dtype:
       class_label:
         names:
-          0: AGAINST
-          1: FAVOR
-          2: NEUTRAL
+          '0': AGAINST
+          '1': FAVOR
+          '2': NEUTRAL
   splits:
   - name: train
     num_bytes: 1507388