Null-Safe rubber 1.0.1 depends on NON-Null-Safe after_layout 1.0.7

[paul-appliquette]

Describe the bug
dart migrate results in Bad state: Error: package has unmigrated dependencies. due to non-null-safe dependency of rubber 1.0.1.

To Reproduce
Run dart migrate on a project that has a dependency on rubber 1.0.1.

Expected behavior
The "Null-Safe" rubber 1.0.1 should not result in the "has unmigrated dependencies" error.

To Fix
Bump the after_layout dependency from the non-null-safe version 1.0.7 to the null-safe 1.1.0 version.