Add a note about the breaking change in getDates method when switching to Laravel 10

[mgralikowski]

Upgrade to Laravel 10 forced to move all attributes from $dates to $casts. It was a breaking change as we were struggling with a lot of errors related to forms.

It turned out that it was caused by the change in the getDates() method.

Example of usage of this method: https://github.com/LaravelCollective/html/blob/64ddfdcaeeb8d332bd98bef442bef81e39c3910b/src/Eloquent/FormAccessible.php#L31

Generally, I think the name of this method now is misleading a bit, as it is limited only to timestamps.
I am not the only one who noticed that -> laravel/framework#42587 (comment)

[taylorotwell]

It still returns a list of "date" fields.

[mgralikowski]

@taylorotwell, no. It doesn't as there is no more $dates attribute available.

Before the update, on average it returned me 3-6 dates (Carbon objects), after the upgrade it is limited to only 2 timestamps. I have an application with ~25 models where $dates was used, so after an update, I had a lot of Call to a member function format() on string errors and I spent 2 hours to find out what is the reason. I just wanted to save people time.

Sadly, in my case, there is easy no fix for this, as getDates is used by a third-party library. But in case using this method directly in-app code, thanks to this information, I would know, that I have to expect different results, and probably prepare my own method to "get dates" in a model, as you did not accept my PR.