Issue: [role]s do not have all required [aria-*] attributes

[sharonytlau]

Hi, I run a Lighthouse check on my site and discovered one disabled combobox element failing a rule.

[role]s do not have all required [aria-*] attributes
Some ARIA roles have required attributes that describe the state of the element to screen readers. Learn more about roles and required attributes.

By looking at the W3C specs on combobox and experimenting with the elements, I confirmed that the failed check was due to a lack of the aria-expanded attribute value on the element.

Link to code example: https://codesandbox.io/p/sandbox/blissful-jackson-5jl9mj

The combobox on the right-hand side is disabled, and it does not have aria-expanded

compared to the normal one on the left-hand side

I believe the following source code has caused this behavior:

// packages\@headlessui-react\src\components\combobox\combobox.tsx
let ourProps = {
    ...,
    'aria-expanded': data.disabled ? undefined : data.comboboxState === ComboboxState.Open,
    ...,
}

I would love to hear the reasoning behind current behavior of making aria-expanded undefined when the element is disabled. As per W3C specs, aria-expanded is required on combobox elements, and there's an accessibility check on it. If current practice is more recommended, could someone link some materials for me to refer to? Thanks a lot!