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

@@ -35,15 +35,15 @@ dataset_info:
     dtype:
       class_label:
         names:
-          0: divergent
-          1: equivalent
+          '0': divergent
+          '1': equivalent
   - name: all_labels
     dtype:
       class_label:
         names:
-          0: unrelated
-          1: some_meaning_difference
-          2: no_meaning_difference
+          '0': unrelated
+          '1': some_meaning_difference
+          '2': no_meaning_difference
   - name: rationale_en
     dtype: string
   - name: rationale_fr