[] flutter pub upgrade
Resolving dependencies...
Because icon_font_generator >=4.0.0 depends on logger ^1.3.0 and yourapp depends on logger ^2.0.1, icon_font_generator >=4.0.0 is forbidden.
So, because yourapp depends on icon_font_generator ^4.0.0, version solving failed.
You can try the following suggestion to make the pubspec resolve:
* Consider downgrading your constraint on icon_font_generator: flutter pub add dev:icon_font_generator:^3.2.0
exit code 1