MacOS icons not rounded?

### :information_source: Info

Version: `v0.12.0`

### :speech_balloon: Description

Are we supposed to use an image that already has a border-radius in order to generate a rounded app-icon for MacOS?

### :scroll: Pubspec.yaml

```yaml
name: test_app
description: A new Flutter project.

version: 1.0.0+1

environment:
sdk: '>=2.18.5 <3.0.0'

dependencies:
flutter:
sdk: flutter
cupertino_icons: ^1.0.2

dev_dependencies:
flutter_launcher_icons: ^0.12.0

flutter_icons:
android: "launcher_icon"
ios: true
image_path: "assets/icon/icon_bg.png"
min_sdk_android: 21 # android min sdk min:16, default 21
web:
generate: true
background_color: "#hexcode"
theme_color: "#hexcode"
windows:
generate: true
icon_size: 48 # min:48, max:256, default: 48
macos:
generate: true

# For information on the generic Dart part of this file, see the
# following page: https://dart.dev/tools/pub/pubspec

# The following section is specific to Flutter packages.
flutter:

# The following line ensures that the Material Icons font is
# included with your application, so that you can use the icons in
# the material Icons class.
uses-material-design: true
# To add assets to your application, add an assets section, like this:
assets:
- google_fonts/
- assets/

```