feat: downgrade langchain-google-genai due to conflict (google-gemini/deprecated-generative-ai-python#738)

Author: tiviluson

backend/requirements.txt

@@ -43,7 +43,7 @@ jupyter_core==5.8.1
 jupyterlab_widgets==3.0.15
 kiwisolver==1.4.8
 langchain-core==0.3.67
-langchain-google-genai==2.1.6
+langchain-google-genai==2.0.10
 langgraph==0.5.0
 langgraph-checkpoint==2.1.0
 langgraph-prebuilt==0.5.2