Model: Add support for chat_template.json

HuggingFace separated the chat template in the newest transformers
versions.

Signed-off-by: kingbri <bdashore3@proton.me>

backends/exllamav2/model.py

@@ -389,6 +389,10 @@ class ExllamaV2Container:
         logger.info("Attempting to load a prompt template if present.")
 
         find_template_functions = [
+            lambda: PromptTemplate.from_model_json(
+                pathlib.Path(self.config.model_dir) / "chat_template.json",
+                key="chat_template",
+            ),
             lambda: PromptTemplate.from_model_json(
                 pathlib.Path(self.config.model_dir) / "tokenizer_config.json",
                 key="chat_template",