fix embeding model for Azure (#1601)

### What problem does this PR solve?

#1599

### Type of change

- [x] Bug Fix (non-breaking change which fixes an issue)

rag/llm/embedding_model.py

         return np.array(res.data[0].embedding), res.usage.total_tokens
 
 
-class AzureEmbed(Base):
+class AzureEmbed(OpenAIEmbed):
     def __init__(self, key, model_name, **kwargs):
         self.client = AzureOpenAI(api_key=key, azure_endpoint=kwargs["base_url"], api_version="2024-02-01")
         self.model_name = model_name
 
+
 class BaiChuanEmbed(OpenAIEmbed):
     def __init__(self, key,
                  model_name='Baichuan-Text-Embedding',