Merge pull request #5067 from open-webui/dependabot/pip/backend/dev/langchain-0.2.15

build(deps): bump langchain from 0.2.14 to 0.2.15 in /backend

backend/requirements.txt

@@ -34,7 +34,7 @@ anthropic
 google-generativeai==0.7.2
 tiktoken
 
-langchain==0.2.14
+langchain==0.2.15
 langchain-community==0.2.12
 langchain-chroma==0.1.2