The dashboard login was failing with "Method Not Allowed" error because
Cachet's service providers were not properly registered in Laravel 11's
bootstrap/providers.php file. This caused Filament authentication routes
to not be loaded, resulting in only GET routes being available for login.
This commit adds the missing CachetCoreServiceProvider and
CachetDashboardServiceProvider to the providers array, which resolves
the login functionality and ensures all Filament routes are properly
registered.
Fixes#4533
