Changes to ActiveModel#numericality in 5.2.1 break ActiveAttr

[edzhelyov]

Steps to reproduce

Gist with runnable code

After the changes in fe9547b the tests from the gist started to fail in my project.
While the PR #33654 attempts to fix other regressions it won't fix the issues with ActiveAttr.

The specs will pass if we remove the type: Integer cast from the attributes, so it's related to the type cast ActiveAttr makes I assume, but haven't dig dipper into both ActiveModel changes and ActiveAttr code.

I'm including @cgriego (the ActiveAttr's author) as he might have suggestions.

/cc @kamipo

System configuration

Rails version: 5.2.1

Ruby version: 2.5.1