Update configuration_eagle_chat.py

Thank you for the model!
There's an issue with the to_dict method in this file where it's not properly loading the vision_config.
This needs to be fixed.

error messages:

File "/home/wjk/yongwoo/mteb-fork/mteb/.venv/lib/python3.10/site-packages/transformers/configuration_utils.py", line 871, in to_diff_dict
class_config_dict = self.__class__().to_dict() if not self.has_no_defaults_at_init else {}
File "/home/wjk/.cache/huggingface/modules/transformers_modules/nvidia/llama-nemoretriever-colembed-1b-v1/1f0fdea7f5b19532a750be109b19072d719b8177/configuration_eagle_chat.py", line 86, in to_dict
output['vision_config'] = self.vision_config.to_dict()
File "/home/wjk/yongwoo/mteb-fork/mteb/.venv/lib/python3.10/site-packages/transformers/configuration_utils.py", line 211, in __getattribute__
return super().__getattribute__(key)
AttributeError: 'llama_NemoRetrieverColEmbedConfig' object has no attribute 'vision_config'

configuration_eagle_chat.py

@@ -40,7 +40,7 @@ class Eagle2ChatConfig(PretrainedConfig):
         super().__init__(**kwargs)
 
         if vision_config is None:
-            vision_config = {}
+            self.vision_config = {}
             logger.info('vision_config is None. Initializing Vision Encoders with default values.')
         else:
             if vision_config['model_type'] == 'siglip_vision_model':