Fix AutoTokenizer mapping

tokenizer_config.json

@@ -1 +1,10 @@
-{"model_type": "chess_transformer"}
+{
+    "model_type": "chess_transformer",
+    "auto_map": {
+        "AutoTokenizer": [
+            "tokenizer.ChessTokenizer",
+            null
+        ]
+    },
+    "tokenizer_class": "ChessTokenizer"
+}