Update tokenizer_config.json

Fixing bug raised in https://huggingface.co/Unbabel/TowerBase-7B-v0.1/discussions/1#65a5b18cc980ec22966b4a8c

tokenizer_config.json

@@ -72,8 +72,8 @@
   "legacy": false,
   "mask_token": "<MASK>",
   "model_max_length": 1000000000000000019884624838656,
-  "pad_token": "<PAD>",
-  "padding_side": "right",
+  "pad_token": "</s>",
+  "padding_side": "left",
   "sep_token": "<SEP>",
   "sp_model_kwargs": {},
   "tokenizer_class": "LlamaTokenizer",