Lumen Mailable ShouldQueue not queuing

i am working on Lumen 6.0 and i have come across a very strange issue.

i am trying to send the emails on mailable queue using ShouldQueue on my mailable class, but it would seem that mails are going normally not sending through a queue, as ShouldQueue should do automatically for all emails. i am using eloquent observers to detect events and then send emails

my Observer

use App\Contact;
use App\Mail\ContactMail;
use Illuminate\Support\Facades\Mail;

class ContactObserver
{
    /**
     * Handle the Account "created" event.
     *
     * @param Contact $contact
     * @return void
     */
    public function created(Contact $contact)
    {
        if (env('MAIL_ENABLED')) // boolean value in .env
            Mail::to(['[email protected]'])->send(new ContactMail($contact));
    }
}

my Mailable

use App\Contact;
use Illuminate\Bus\Queueable;
use Illuminate\Contracts\Queue\ShouldQueue;
use Illuminate\Mail\Mailable;
use Illuminate\Queue\SerializesModels;

class ContactMail extends Mailable implements ShouldQueue
{
    use Queueable, SerializesModels;

    public $contact;

    /**
     * Create a new message instance.
     *
     * @param Contact $contact
     */
    public function __construct(Contact $contact)
    {
        $this->contact = $contact;
    }

    /**
     * Build the message.
     *
     * @return $this
     */
    public function build()
    {
        return $this->subject("Contact - " . config('app.name'))->from(config('mail.from'))->markdown('emails.contact.new');
    }
}

my ServiceProvider

use App\Contact;
use App\Observers\ContactObserver;
use Illuminate\Contracts\Container\BindingResolutionException;
use Illuminate\Support\Facades\Schema;
use Illuminate\Support\ServiceProvider;

class AppServiceProvider extends ServiceProvider
{
    /**
     * Bootstrap any application services.
     *
     * @return void
     * @throws BindingResolutionException
     */
    public function boot()
    {
        Schema::defaultStringLength(191);

        $this->app->make('queue');  // without this i get >> Argument 1 passed to Illuminate\Mail\Mailable::queue() must be an instance of Illuminate\Contracts\Queue\Factory, null given, called in /var/www/html/vendor/illuminate/mail/Mailer.php on line 388

        Contact::observe(ContactObserver::class);
    }
}