Running checks conditionally

[stfndamjanovic]

This PR is adding the possibility to run some checks only under certain conditions.

use Spatie\Health\Facades\Health;
use Spatie\Health\Checks\Checks\DebugModeCheck;
use Spatie\Health\Checks\Checks\RedisCheck;

Health::checks([
    DebugModeCheck::new()->if(app()->isProduction()),
    RedisCheck::new()->unless(app()->environment('development')),
]);

[freekmurze]

Thank you!