Add Openai gpt-5.3-codex model into my Openai web application

Here is My Openai Chat Github Repository

To add gpt-5.3-codex model

• Update Dockerfile to use python:3.9 base image.
• Update requirements.txt to use Django 4.2.0 and Python openai sdk 2.26.0
• Use Python openai sdk response api to interact with Openai gpt-5.3-codex model