Update pydantic to version 2.11.7

Bumped pydantic from 2.5.3 to 2.11.7 in requirements.txt to include the latest features and bug fixes.

Author: ThomasJButler

backend/requirements.txt

@@ -5,7 +5,7 @@ langchain-openai==0.1.25
 langchain-community==0.2.17
 chromadb==0.4.24
 python-dotenv==1.0.0
-pydantic==2.5.3
+pydantic==2.11.7
 pandas==2.1.4
 numpy==1.26.2
 python-multipart==0.0.6