Laravel Lumen Tracing issue

Changes made in #707 cause an exception to be thrown when using the SDK >= v3.5.0 with Laravel Lumen v10 (and likely others).

```php
Sentry\Laravel\Tracing\Middleware::__construct(): Argument #1 ($app) must be of type ?Illuminate\Contracts\Foundation\Application, Laravel\Lumen\Application given
```

