Align label mapping with imdb dataset

config.json

@@ -37,5 +37,13 @@
   "transformers_version": "4.19.1",
   "truncate_seq": true,
   "type_vocab_size": 3,
-  "vocab_size": 30522
-}
+  "vocab_size": 30522,
+  "label2id": {
+    "neg": 0,
+    "pos": 1
+  },
+  "id2label": {
+    "0": "neg",
+    "1": "pos"
+  }
+}