message: Checkbox label is now `impl Into<String>`
diff: @@ -50,14 +50,14 @@ impl<Message, Renderer: self::Renderer + text::Renderer>
  /// `Message`.
  ///
  /// [`Checkbox`]: struct.Checkbox.html
  - pub fn new<F>(is_checked: bool, label: &str, f: F) -> Self
  + pub fn new<F>(is_checked: bool, label: impl Into<String>, f: F) -> Self
  where
  F: 'static + Fn(bool) -> Message,
  {
  Checkbox {
  is_checked,
  on_toggle: Box::new(f),
  - label: String::from(label),
  + label: label.into(),
  width: Length::Shrink,
  size: <Renderer as self::Renderer>::DEFAULT_SIZE,
  spacing: Renderer::DEFAULT_SPACING,
  