Update wayland-client dependency to fix wl_shm errors.

[eddyb]

I've been living with this error (and having to force X11 via XWayland, by clearing WAYLAND_DISPLAY):

[wayland-client error] Attempted to dispatch unknown opcode 0 for wl_shm, aborting.

Turns out that winit's code doesn't need to change whenever many of the protocols are updated!
So we can just bump the wayland-* libraries from 0.29.1 to 0.29.5 (0.29.3 fixed the above error).

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Related PRs that we thankfully don't need to wait on (but which may be interesting):

• Update wgpu (and ash, to avoid duplicate deps). #925
• Update wayland-rs to 0.30.0 rust-windowing/winit#2676