Update wayland-sys requirement from 0.30.0 to 0.31.0

Updates the requirements on [wayland-sys](https://github.com/smithay/wayland-rs) to permit the latest version.
- [Release notes](https://github.com/smithay/wayland-rs/releases)
- [Changelog](https://github.com/Smithay/wayland-rs/blob/master/historical_changelog.md)
- [Commits](https://github.com/smithay/wayland-rs/commits)

---
updated-dependencies:
- dependency-name: wayland-sys
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <[email protected]>

Cargo.toml

@@ -35,7 +35,7 @@ nix = { version = "0.26.1", optional = true }
 tiny-xlib = { version = "0.2.1", optional = true }
 wayland-backend = { version = "0.1.0", features = ["client_system"], optional = true }
 wayland-client = { version = "0.30.0", optional = true }
-wayland-sys = "0.30.0"
+wayland-sys = "0.31.0"
 x11rb = { version = "0.12.0", features = ["allow-unsafe-code", "shm"], optional = true }
 
 [target.'cfg(all(unix, not(any(target_vendor = "apple", target_os = "android", target_os = "redox", target_os = "linux", target_os = "freebsd"))))'.dependencies]