Fix Laravel Nova 4 support

[nicko170]

Nova 4 has started using NovaRequest instead of request in ->actions() and ->filters(). All my tests were failing with :

App\Nova\Resources\ChangeApproval::actions(): Argument #1 ($request) must be of type Laravel\Nova\Http\Requests\NovaRequest, Illuminate\Http\Request given, called in /Users/nickp/Documents/GitHub/ixport.al/vendor/joshgaber/novaunit/src/Traits/ActionAssertions.php on line 26

[joshgaber]

Thank you for bringing this to my attention. I will need to fix up the unit tests to account for this change before I can release it. I will deploy a new version ASAP.