Added support for Baichuan LLM (#934)

### What problem does this PR solve?

- Added support for Baichuan LLM

### Type of change

- [x] New Feature (non-breaking change which adds functionality)

Co-authored-by: 海贼宅 <stu_xyx@163.com>

rag/llm/embedding_model.py

@@ -104,6 +104,15 @@ class OpenAIEmbed(Base):
         return np.array(res.data[0].embedding), res.usage.total_tokens
 
 
+class BaiChuanEmbed(OpenAIEmbed):
+    def __init__(self, key,
+                 model_name='Baichuan-Text-Embedding',
+                 base_url='https://api.baichuan-ai.com/v1'):
+        if not base_url:
+            base_url = "https://api.baichuan-ai.com/v1"
+        super().__init__(key, model_name, base_url)
+
+
 class QWenEmbed(Base):
     def __init__(self, key, model_name="text_embedding_v2", **kwargs):
         dashscope.api_key = key