Use data_get() for placeholder replacement instead of Arr::get()

[stevebauman]

Description

This PR replaces the usage of Arr::get() with data_get() for retrieving placeholder values, so model properties (and deeply nested properties) can be logged.

Problem

In the documentation it states:

These placeholders will get replaced with the properties of the given subject, causer or property.

However, this is not the case, as model properties cannot be reached with placeholders -- only model attributes.

Also, calling $model->toArray() inadvertently executes and caches model accessors via the $appends property, which can cause unneeded overhead if a developer has configured queries to be executed in these accessors.

This PR resolves the above issues by using Laravel's data_get() helper, which reaches into objects (and deeply nested objects) via dot-notated key.

[Gummibeer]

Thanks for the fix! 🎉

[Gummibeer]

https://github.com/spatie/laravel-activitylog/releases/tag/4.5.2

[stevebauman]

Happy to help @Gummibeer!