fix: Use raw-window-handle 0.6

[mwcampbell]

Following up on an earlier comment, I don't think it would be right for us to do a new release that depends on an old version of raw-window-handle, if we can easily avoid it. So this PR switches accesskit_winit to use rwh_06. @Vrixyz I believe this can coexist with your code that requires rwh_05, since it seems that those winit features don't actually conflict, but please check.

[DataTriny]

The code is OK for me indeed!

Mxing raw-window-handle versions seem to never be an option from the GitHub issues I checked on various projects. Therefore I would prefer more input from users before merging.

[Vrixyz]

Yes, I believe your understanding is correct, 2 different versions of rwh should be able to coexist. I'm not sure how to convert from 1 version to the other, I'd guess the pointers are compatible but might require some shenanigans 🤔.

For the record, I initially didn't update to rwh_06 because wgpu wasn't supporting it either, so it gave me enough incentive to not update.

by next bevy version (0.13 ; I guess ~march 2024), we'll probably have an updated wgpu version and no blockers to support only rwh_06, I don't think I'll champion those changes, but that should ease the integration if accesskit upgrades to rwh_06.

[mwcampbell]

Since winit itself has rwh_06 as a default feature now, I think it's better for us to use that version. Going to merge.

[Vrixyz]

Hey, with bevy winit/accesskit update, I realized having multiple version is not pleasing our CI (we're trying to avoid duplicate dependencies). Would you be against having a feature rwh_05 ?

Pretty much reverting your changes behind a feature flag akin to how winit do it.