Fix transformers version conflict

- Update transformers from 4.36.0 to 4.39.0
- Resolve langchain-huggingface dependency requirement >=4.39.0
- Fix ResolutionImpossible error for transformers package

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <[email protected]>

requirements.txt

@@ -13,7 +13,7 @@ langchain-core==0.2.11
 langchain-huggingface==0.0.3
 sentence-transformers==2.6.0
 faiss-cpu==1.7.4
-transformers==4.36.0
+transformers==4.39.0
 torch==2.1.0
 tokenizers==0.19.1
 pydantic==2.5.0