## Summary
Under preview 🧪 I've expanded rule `PYI016` to also flag type
union duplicates containing `None` and `Optional`.
## Test Plan
Examples/tests have been added. I've made sure that the existing
examples did not change unless preview is enabled.
## Relevant Issues
* https://github.com/astral-sh/ruff/issues/18508 (discussing
introducing/extending a rule to flag `Optional[None]`)
* https://github.com/astral-sh/ruff/issues/18546 (where I discussed this
addition with @AlexWaygood)
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Co-authored-by: Brent Westbrook <36778786+ntBre@users.noreply.github.com>
Co-authored-by: Brent Westbrook <brentrwestbrook@gmail.com>