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

@@ -29,11 +29,11 @@ dataset_info:
     dtype:
       class_label:
         names:
-          0: Personal
-          1: Political
-          2: Religious
-          3: Geopolitical
-          4: Gender abusive
+          '0': Personal
+          '1': Political
+          '2': Religious
+          '3': Geopolitical
+          '4': Gender abusive
   splits:
   - name: train
     num_bytes: 972635