fix: avoid mass assignment

[jaulz]

I would like to avoid setting $fillable at all. This approach would set attributes one by one and does the same thing without causing any exception in strict mode.

[tonysm]

Isn't it already possible to unguard all models at the application-level? I feel like that's a decision that should be done at the application-level. Don't see why we should bypass what's defined in the app.

[jaulz]

@tonysm I think the getChildModel is a method that shouldn't depend on the application settings. It should just work in every Laravel application the same way shouldn't it?