[Docs Agent] Update the Python version to 3.12.8 and fix syntax errors

[kyolee415]

Description of the change

Update Docs Agent to support Python 3.12.8 and fix syntax errors detected by Python 3.12.8

Motivation

To make Docs Agent compatible with Python v3.12.8

Type of change

Choose one: (Bug fix)

Checklist

• [ X] I have performed a self-review of my code.
• [ X] I have added detailed comments to my code where applicable.
• [ X] I have verified that my change does not break existing code.
• [ X] My PR is based on the latest changes of the main branch (if unsure, please run git pull --rebase upstream main).
• [ X] I am familiar with the Google Style Guide for the language I have coded in.
• [ X] I have read through the Contributing Guide and signed the Contributor License Agreement.