chore(rustfmt): use nightly (#2325)

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

src/platform_impl/web/event_loop/state.rs

@@ -5,17 +5,9 @@ use web_time::Instant;
 #[derive(Debug)]
 pub enum State {
     Init,
-    WaitUntil {
-        _timeout: backend::Schedule,
-        start: Instant,
-        end: Instant,
-    },
-    Wait {
-        start: Instant,
-    },
-    Poll {
-        _request: backend::Schedule,
-    },
+    WaitUntil { _timeout: backend::Schedule, start: Instant, end: Instant },
+    Wait { start: Instant },
+    Poll { _request: backend::Schedule },
     Exit,
 }