[`flake8-pyi`] Make example error out-of-the-box (`PYI062`) (#19079)
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## Summary
<!-- What's the purpose of the change? What does it do, and why? -->
Part of #18972
This PR makes [duplicate-literal-member
(PYI062)](https://docs.astral.sh/ruff/rules/duplicate-literal-member/#duplicate-literal-member-pyi062)'s
example error out-of-the-box
[Old example](https://play.ruff.rs/6b00b41c-c1c5-4421-873d-fc2a143e7337)
```py
foo: Literal["a", "b", "a"]
```
[New example](https://play.ruff.rs/1aea839b-9ae8-4848-bb83-2637e1a68ce4)
```py
from typing import Literal
foo: Literal["a", "b", "a"]
```
Imports were also added to the "use instead" section.
## Test Plan
<!-- How was it tested? -->
N/A, no functionality/tests affected