Null Safety Error after changing stacked_generator version

I have been following your channel in the Box't Out project. In the section of implementing the Login and Sign up pages, you asked that the stacked_generator library is changed to version ^0.2.4 . I immediately go the following error after making that change.

[customer] flutter pub get
Running "flutter pub get" in customer...
The current Dart SDK version is 2.10.5.

Because stacked_generator >=0.2.4 depends on analyzer >=0.42.0-nullsafety.0 which requires SDK version >=2.12.0-0 <3.0.0, stacked_generator >=0.2.4 is forbidden.

So, because customer depends on stacked_generator ^0.2.4, version solving failed.
pub get failed (1; So, because customer depends on stacked_generator ^0.2.4, version solving failed.)
exit code 1

Please Help. Flutter version (1.22.6)