Nova v5 Support

[nw-b]

Nova 5 has dropped! This package needs to be updated to support the new version.
https://nova.laravel.com/docs/v5/releases

  Problem 3
    - Root composer.json requires spatie/nova-tags-field ^4.0 -> satisfiable by spatie/nova-tags-field[4.0.0, ..., 4.0.8].
    - spatie/nova-tags-field[4.0.0, ..., 4.0.3] require laravel/nova ^4.0 -> found laravel/nova[4.0.0, ..., 4.35.5] but it conflicts with your root composer.json require (^5.0).
    - spatie/nova-tags-field[4.0.4, ..., 4.0.8] require laravel/nova ^4.13 -> found laravel/nova[4.13.0, ..., 4.35.5] but it conflicts with your root composer.json require (^5.0).

[freekmurze]

I'd accept a PR that makes this package compatible with Nova 5

[crynobone]

@freekmurze can you make a separate branch to accept such PR? Nova 5 contains multiple breaking changes and it would be hard to allow both Nova 4 and 5.