Change the value of add_eos_token to false

From what I can see in the `tokenizer_config.json` of plamo-13b-instruct, it seems better for the value of this option to be false.
https://huggingface.co/pfnet/plamo-13b-instruct/blob/main/tokenizer_config.json#L3

tokenizer_config.json

@@ -1,6 +1,6 @@
 {
     "add_bos_token": false,
-    "add_eos_token": true,
+    "add_eos_token": false,
     "added_tokens_decoder": {
         "0": {
             "content": "<unk>",