Because simple_file_saver >=2.0.0 depends on simple_file_saver_platform_interface ^2.0.0 which depends on mime ^1.0.5, simple_file_saver >=2.0.0 requires mime ^1.0.5.
So, because easyhour_app depends on both simple_file_saver ^2.0.1 and mime ^2.0.0, version solving failed.
The project depends on mime 1.x which is outdated:
Upgrading to mime 2.x should pretty straightforward, see https://pub.dev/packages/mime/changelog