Fix AutoTokenizer mapping to use list format to avoid parsing error

config.json

@@ -13,6 +13,6 @@
   "auto_map": {
     "AutoConfig": "configuration_ablang2paired.AbLang2PairedConfig",
     "AutoModel": "modeling_ablang2paired.AbLang2PairedHFModel",
-    "AutoTokenizer": "tokenizer_ablang2paired.AbLang2PairedTokenizer"
+    "AutoTokenizer": ["tokenizer_ablang2paired.AbLang2PairedTokenizer", null]
   }
 }