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

@@ -25,20 +25,20 @@ dataset_info:
     dtype:
       class_label:
         names:
-          0: Company
-          1: EducationalInstitution
-          2: Artist
-          3: Athlete
-          4: OfficeHolder
-          5: MeanOfTransportation
-          6: Building
-          7: NaturalPlace
-          8: Village
-          9: Animal
-          10: Plant
-          11: Album
-          12: Film
-          13: WrittenWork
+          '0': Company
+          '1': EducationalInstitution
+          '2': Artist
+          '3': Athlete
+          '4': OfficeHolder
+          '5': MeanOfTransportation
+          '6': Building
+          '7': NaturalPlace
+          '8': Village
+          '9': Animal
+          '10': Plant
+          '11': Album
+          '12': Film
+          '13': WrittenWork
   - name: title
     dtype: string
   - name: content