delete weight_type in knowledge retrieval node (#6892)

api/core/workflow/nodes/knowledge_retrieval/entities.py

     """
     Weighted score Config.
     """
-    weight_type: str
     vector_setting: VectorSetting
     keyword_setting: KeywordSetting
 
     reranking_model: Optional[RerankingModelConfig] = None
     weights: Optional[WeightedScoreConfig] = None
 
-
 class ModelConfig(BaseModel):
     """
      Model Config.

api/core/workflow/nodes/knowledge_retrieval/knowledge_retrieval_node.py

             elif node_data.multiple_retrieval_config.reranking_mode == 'weighted_score':
                 reranking_model = None
                 weights = {
-                    'weight_type': node_data.multiple_retrieval_config.weights.weight_type,
                     'vector_setting': {
                         "vector_weight": node_data.multiple_retrieval_config.weights.vector_setting.vector_weight,
                         "embedding_provider_name": node_data.multiple_retrieval_config.weights.vector_setting.embedding_provider_name,