Align label mapping with imdb dataset

config.json

@@ -20,5 +20,13 @@
   "transformers_version": "4.5.1",
   "type_vocab_size": 2,
   "use_cache": true,
-  "vocab_size": 28996
-}
+  "vocab_size": 28996,
+  "label2id": {
+    "neg": 0,
+    "pos": 1
+  },
+  "id2label": {
+    "0": "neg",
+    "1": "pos"
+  }
+}