`reportUninitializedInstanceVariable` false negatives/positives for the `__weakref__` slot

Describe the bug
When reportUninitializedInstanceVariable is true, pyright reports an error stating that __weakref__ is not initialized (false positive), even though it should never be initialized by the user. Interestingly, this only happens when the slot is defined via a sequence, but is ignored when defined via a string (false negative?).

Code or Screenshots

#!/usr/bin/env python3
# pyright: reportUninitializedInstanceVariable = true

import weakref


class EmptyViaString:
    __slots__ = "__weakref__"


class EmptyViaTuple:
    __slots__ = ("__weakref__",)


def main() -> None:
    weakref.ref(EmptyViaString())  # ok
    weakref.ref(EmptyViaTuple())  # ok


if __name__ == "__main__":
    main()

/home/user/workspace/example.py
  /home/user/workspace/example.py:12:18 - error: Instance variable "__weakref__" is not initialized in the class body or __init__ method (reportUninitializedInstanceVariable)
1 error, 0 warnings, 0 informations

Start with the provided Python reproducer and compare Pyright's handling of slots when it is a string versus a sequence. Trace the uninitialized-instance-variable analysis for weakref; done means both examples are accepted without false positives while the intended diagnostic remains intact.