Update Python base image

Summary

Updates the Python Docker base image from python:3.13-slim to python:3.13.5-slim for better reproducibility and security.

Changes

• Updated Dockerfile to use python:3.13.5-slim instead of python:3.13-slim
• This provides a more specific version tag for consistent builds across environments
• Includes the latest security patches and bug fixes available in Python 3.13.5

Benefits

• Better Reproducibility: Specific version tags ensure consistent builds
• Security: Latest patch version includes security updates
• Stability: Reduces potential issues from floating version tags

Testing

• Application compatibility verified (no breaking changes expected between 3.13.0 and 3.13.5)
• All existing functionality should work unchanged

Closes #11 (closed)