[3x] fix Implicitly nullable parameters are deprecated.

[GustavoSantarosa]

I know Laravel 10 lost the support, but this is a slight adjustment so as not to generate more boring depreciation errors, please take advantage

ErrorException: Laravel\Sanctum\Guard::isValidBearerToken(): Implicitly marking parameter $token as nullable is deprecated, the explicit nullable type must be used instead in /var/task/vendor/laravel/sanctum/src/Guard.php:131
Stack trace:
#0 /var/task/vendor/laravel/framework/src/Illuminate/Support/helpers.php(445): Illuminate\Foundation\Bootstrap\HandleExceptions->{closure:Illuminate\Foundation\Bootstrap\HandleExceptions::handleDeprecationError():102}(Object(Illuminate\Log\Logger))