fix: update datetime timezone reference to maintain compatibility wit…

[gitricko]

This pull request makes a minor update to the way UTC timestamps are generated in mnemon/__init__.py. The change replaces the use of datetime.UTC with the correct timezone.utc for creating timezone-aware timestamps. This ensures compatibility with the standard library and avoids potential errors.

• Updated timestamp creation to use timezone.utc instead of the incorrect datetime.UTC in mnemon/__init__.py. [1] [2]…h older Python versions

[Copilot]

Pull request overview

Updates UTC timestamp generation in MnemonMemoryProvider to use timezone.utc instead of datetime.UTC, keeping stored index timestamps timezone-aware while improving compatibility with Python environments that may not expose datetime.UTC.

Changes:

• Import timezone from datetime.
• Replace datetime.now(datetime.UTC) with datetime.now(timezone.utc) when writing "ts" in the local ID index.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.