Feature: upgrade from `dateutil.tz.UTC` to `datetime.UTC` or `datetime.timezone.utc`

there are some legacy code using `dateutil.tz.UTC` as UTC timezone, suggest a new rule to replace it with `datetime.UTC` for python >= 3.11

No implementation files or tests are named. Start by locating Ruff’s existing rule definitions and tests for comparable modernization rules, then verify how Python 3.11-only replacements are handled. Done means the new rule consistently identifies dateutil.tz.UTC usage, recommends the specified datetime replacement, and has coverage for supported cases.

Written by the indexing model from the issue text.