unbindKey static method
Unbinds the handler from the key.
Implementation
static Future<void> unbindKey(HotKey key, bool Function() handler) async {
  final list = _keyHandlers[key];
  list?.remove(handler);
  if (list?.isEmpty == true) {
    _keyHandlers.remove(key);
  }
  if (_keyHandlers.isEmpty) {
    HardwareKeyboard.instance.removeHandler(_handleBindKeys);
  }
}