Update icons files

[ikbendewilliam]

⚠ Warning: flutter_icons has been deprecated please use flutter_launcher_icons instead in your yaml files
...
WARNING: Icons with alpha channel are not allowed in the Apple App Store.
Set "remove_alpha_ios: true" to remove it.

[ikbendewilliam]

adaptive_icon_foreground should also already be specified so we don't forget to add it as the adaptive icon will not generate otherwise