I have a problem implementing PDF-RAG, since there is no OpenAI API, I want to try local llm, but it is not clear how to configure PDFSearchTool. Error Info： File "/home/an/Desktop/crewAI/.venv/lib/python3.11/site-packages/embedchain/app.py", line 121, in __init__ self.embedding_model = embedding_model or OpenAIEmbedder() ^^^^^^^^^^^^^^^^ File "/home/an/Desktop/crewAI/.venv/lib/python3.11/site-packages/embedchain/embedder/openai.py", line 19, in __init__ api_key = self.config.api_key or os.environ["OPENAI_API_KEY"] ~~~~~~~~~~^^^^^^^^^^^^^^^^^^ File "<frozen os>", line 679, in __getitem__