Fix TogetherAIEmbed. (#4623)

### What problem does this PR solve?

#4567

### Type of change

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

rag/llm/embedding_model.py

@@ -627,7 +627,7 @@ class CoHereEmbed(Base):
         )
 
 
-class TogetherAIEmbed(OllamaEmbed):
+class TogetherAIEmbed(OpenAIEmbed):
     def __init__(self, key, model_name, base_url="https://api.together.xyz/v1"):
         if not base_url:
             base_url = "https://api.together.xyz/v1"