fix : replace deprecated datetime.utcnow in code_review.py

[tmdeveloper007]

Summary of What Needs to be Done

Replace all occurrences of the deprecated with the timezone-aware in . This addresses the Python 3.12+ deprecation warning for naive UTC datetime objects.

Changes that Need to be Made

• In the import statement, change to
• Replace all calls with across the file
• Update any calls that follow to work with the new approach

Impact that it would Provide

• Eliminates Python 3.12+ deprecation warnings for
• Uses the recommended timezone-aware datetime approach throughout the code review module
• Correct timestamp generation for code submissions, reviews, and feedback

Note: Please assign this issue to the tmdeveloper007 account.