Does not generate mac icons when using flavors

### :information_source: Info

```
flutter: ^3.29.2
flutter_launcher_icons: ^0.14.3
```

### :speech_balloon: Description

Does not generate the macOS icons when using flavors

### :scroll: Pubspec.yaml

`flutter_launcher_icons-pro.yaml`
```yaml
flutter_launcher_icons:
android: true
image_path: "launcher/android-free.png"
image_path_ios: "launcher/ios-pro.png"
macos:
generate: true
image_path: "launcher/mac-pro.png"
web:
generate: false
windows:
generate: false
```

Start by reproducing the issue with flutter_launcher_icons-pro.yaml and the macOS flavor configuration shown in the report. Trace the macOS icon-generation entry point and compare it with flavor handling; done means the configured mac-pro.png icons are generated for the flavor without affecting the other platform outputs.

Written by the indexing model from the issue text.