handle relative path in migration file exists check

[mvenghaus]

Hey there,

I'm using your laravel settings package for my own ones. Therefore I have a settings migration file in database/settings.

Now I try to publish these settings like this:

->hasMigrations([
    '../settings/create_mail_settings'
])

First publish works without a problem. But if I run it again it copies the file again because only the migrations path is checked for the file. So I changed the code to resolve the path using the given publish file.

[freekmurze]

Thanks!