support to disable exllama for gptq (#604)

* support to disable exllama for gptq

* update property instead of item

* fix config key

src/axolotl/utils/models.py

@@ -196,6 +196,10 @@ def load_model(
         if not hasattr(model_config, "quantization_config"):
             LOG.warning("model config does not contain quantization_config information")
         else:
+            if cfg.gptq_disable_exllama is not None:
+                model_config.quantization_config[
+                    "disable_exllama"
+                ] = cfg.gptq_disable_exllama
             model_kwargs["quantization_config"] = GPTQConfig(
                 **model_config.quantization_config
             )