Update tokenizer_config.json

Configuring bos, eos, pad and unk tokens helps load the tokenizer successfully, otherwise getting a recursion error "RecursionError: maximum recursion depth exceeded while getting the str of an object." As done here: https://huggingface.co/medalpaca/medalpaca-13b/discussions/7

tokenizer_config.json

@@ -1,9 +1,10 @@
 {
-  "bos_token": "",
-  "eos_token": "",
+  "bos_token": "</s>",
+  "eos_token": "</s>",
   "model_max_length": 512,
   "padding_side": "right",
   "special_tokens_map_file": "../llama-7b-hf/special_tokens_map.json",
   "tokenizer_class": "LlamaTokenizer",
-  "unk_token": ""
+  "unk_token": "</s>",
+  "pad_token": "[PAD]"
 }