Update requirements.txt

requirements.txt

@@ -4,9 +4,8 @@ tiktoken == 0.6.0
 chromadb == 0.4.22
 sentence-transformers == 2.6.0
 pypdf == 5.3.0
-langchain == 0.3.19
-langchain-core == 0.3.37
-langchain-community == 0.3.18
-langchain-chroma == 0.2.2
-langchain-huggingface == 0.1.2
-langchain-openai == 0.3.7
+langchain >= 0.3.19
+langchain-core >= 0.3.39
+langchain-community >= 0.3.18
+langchain-chroma >= 0.2.2
+langchain-openai >= 0.3.7