chore(rustfmt): use nightly (#2325)

Stable rustfmt lacks a lot of features resulting in worse formatted
code, thus use nightly formatter.

src/platform/mod.rs

@@ -51,11 +51,5 @@ pub mod pump_events;
 ))]
 pub mod modifier_supplement;
 
-#[cfg(any(
-    windows_platform,
-    macos_platform,
-    x11_platform,
-    wayland_platform,
-    docsrs
-))]
+#[cfg(any(windows_platform, macos_platform, x11_platform, wayland_platform, docsrs))]
 pub mod scancode;