possible fix for double event registration in child models when calling events from parent trait use

Came across this issue when using `owen-it/laravel-auditing`. My `Model` class uses the `Auditable` trait, but the events are registered twice because `parentIsBooting` only accounts for traits used by the parent class itself, to solve this problem I created a static array for parent classes and added an alternative `isset` verification, similar to the preexisting `$parentBootMethods` logic.