Remove useless parameter

Signed-off-by: Jael Gu <mengjia.gu@zilliz.com>

codebert.py

@@ -45,7 +45,6 @@ class CodeBert(NNOperator):
     def __init__(self, model_name: str = 'huggingface/CodeBERTa-small-v1', device: str = None):
         super().__init__()
         self.model_name = model_name
-        self.modality = modality
         assert modality in ['nlp', 'code'], 'Invalid modality value. Accept only "nlp" or "code".'
 
         if device is None: