Update Bref examples for Bref v2

[mnapoli]

We should update https://github.com/brefphp/examples to use Bref v2 (and also update Symfony and Laravel versions).

Any help is welcome. Baby steps are OK too, for example you can start by upgrading just a Laravel/Symfony version, then introduce Bref v2 (you don't need to tackle all examples at once).

[tillkruss]

Should we use https://github.com/cachewerk/bref-laravel-bridge for this?

[mnapoli]

I still need to look into the migration path and the impact on the DX for Bref users 👍

[mnapoli]

Working on it at brefphp/examples#42