Fix IME input handling (#20)

bevy_winit does not call `set_ime_allowed()` during initial window
creation when `Window::ime_enabled` is `true`. The `changed_windows`
system only fires when the value differs from cache, but the cache
is initialized from the window itself so they start equal. Since
winit 0.27+ requires explicit `set_ime_allowed(true)`, no Ime events
were ever generated.

src/keyboard.rs

@@ -104,7 +104,7 @@ fn ime_event(
                 is_ime_commiting.0 = true;
             }
             Ime::Disabled { .. } => {
-                browsers.ime_finish_composition(false);
+                browsers.ime_cancel_composition();
             }
             _ => {}
         }