partners: Fixed the procedure of initializing pad_token_id

Add to check pad_token_id and eos_token_id of model config.
It seems that this is the same bug as the HuggingFace TGI bug.

libs/partners/huggingface/langchain_huggingface/llms/huggingface_pipeline.py

@@ -202,7 +202,16 @@ def from_model_id(
         model = model_cls.from_pretrained(model_id, **_model_kwargs)
 
         if tokenizer.pad_token is None:
-            tokenizer.pad_token_id = model.config.eos_token_id
+            if model.config.pad_token_id is not None:
+                tokenizer.pad_token_id = model.config.pad_token_id
+            elif model.config.eos_token_id is not None and isinstance(
+                model.config.eos_token_id, int
+            ):
+                tokenizer.pad_token_id = model.config.eos_token_id
+            elif tokenizer.eos_token_id is not None:
+                tokenizer.pad_token_id = tokenizer.eos_token_id
+            else:
+                tokenizer.add_special_tokens({"pad_token": "[PAD]"})
 
         if (
             (