PIE796 false-positives on enum member cast in pyi files

[Avasam]

Found this whilst applying various Ruff groups on typeshed out of curiosity.

According to the updated typing spec for typing enums (see Mypy: Change to Enum Membership Semantics and https://typing.readthedocs.io/en/latest/spec/enums.html#defining-members, this is the recommended way to type an enum in stubs where the type is known but the value isn't:

class Key(enum.Enum):
    alt = cast(KeyCode, ...)
    alt_l = cast(KeyCode, ...)
    alt_r = cast(KeyCode, ...)
    alt_gr = cast(KeyCode, ...)
    # ...

This will trigger PIE796

However I think that a fix could be simpler than that: This rule probably shouldn't apply to stubs as it's out of the control of a stub's author (ref #14535 )

ruff 0.8.4
command: ruff check --select=PIE --isolated

[InSyncWithFoo]

Rather than disabling the entire rule, I think the pattern should simply be ignored for stub files when checking for duplicates. It is possible that a stub author might add two members with the same value by mistake (say, via a copy and paste error).