Remove unused datetime import to fix lint warning

[Lang-Qiu]

This PR addresses a lint warning in .github/scripts/process_item.py where the datetime module was imported but unused due to a redefinition. The warning indicated that datetime from line 3 (import datetime) was redefined by the more specific import on line 6 (from datetime import datetime, timedelta, timezone). Removing the unused import improves code clarity and eliminates the lint issue without affecting functionality.

Changes:

• Removed the import datetime statement on line 3, as the necessary components (datetime, timedelta, timezone) are already imported via from datetime import ... on line 6.

Verification:

• Confirmed that all uses of datetime, timedelta, and timezone in the code remain correctly referenced.
• No functional changes; the script's behavior is unchanged.