FrankenPHP: Remove unnecessary use statement to fix PHP warning

[philbates35]

Currently when running php artisan octane:work --server=frankenphp with full error reporting enabled, the following warning is displayed, which this PR fixes:

WARN  PHP Warning:  The use statement with non-compound name 'Throwable' has no effect in /app/vendor/laravel/octane/bin/frankenphp-worker.php on line 9

---

Steps to reproduce

1. Create a new Laravel app in example-app/ and install octane (type yes to accept still in Beta):

   docker run --rm -it -u $(id -u $USER) -v $PWD:/app composer:latest composer create-project laravel/laravel example-app
   cd example-app
   docker run --rm -it -u $(id -u $USER) -v $PWD:/app composer:latest composer require laravel/octane
   docker run --rm -it -u $(id -u $USER) -v $PWD:/app dunglas/frankenphp:1.0-php8.3 php artisan octane:install --server=frankenphp

2. Create the following Dockerfile:

   FROM dunglas/frankenphp:1.0-php8.3
   
   RUN install-php-extensions pcntl;
   
   # Using php.ini-development enables full error reporting 
   RUN cp $PHP_INI_DIR/php.ini-development $PHP_INI_DIR/php.ini; \
       sed -i 's/variables_order = "GPCS"/variables_order = "EGPCS"/' $PHP_INI_DIR/php.ini;
   
   ENTRYPOINT ["php", "artisan", "octane:start", "--server=frankenphp"]

3. Create the following docker-compose.yml, as per the FrakenPHP docs:

   services:
     php:
       build: .
       ports:
         - 8000:8000
       volumes:
         - ./:/app:z
         - caddy_data:/data:z
         - caddy_config:/config:z
       tty: true
   
   volumes:
     caddy_data:
     caddy_config:

4. Run the following command to start octane

   docker-compose up --build
   Building php
   DEPRECATED: The legacy builder is deprecated and will be removed in a future release.
               Install the buildx component to build images with BuildKit:
               https://docs.docker.com/go/buildx/
   
   Sending build context to Docker daemon  59.64MB
   Step 1/4 : FROM dunglas/frankenphp:1.0-php8.3
    ---> 0cfa433eac62
   Step 2/4 : RUN install-php-extensions pcntl;
    ---> Using cache
    ---> 8c7d04a009a8
   Step 3/4 : RUN cp $PHP_INI_DIR/php.ini-development $PHP_INI_DIR/php.ini;     sed -i 's/variables_order = "GPCS"/variables_order = "EGPCS"/' $PHP_INI_DIR/php.ini;
    ---> Running in 026ced34ecba
   Removing intermediate container 026ced34ecba
    ---> 592b6db9944e
   Step 4/4 : ENTRYPOINT ["php", "artisan", "octane:start", "--server=frankenphp"]
    ---> Running in aef1f1d18d72
   Removing intermediate container aef1f1d18d72
    ---> 1ad87e24ec0d
   Successfully built 1ad87e24ec0d
   Successfully tagged example-app_php:latest
   Recreating example-app_php_1 ... done
   Attaching to example-app_php_1
   
   INFO  Server running…
   
   Local: http://0.0.0.0:8000
   
   Press Ctrl+C to stop the server
   
      WARN  PHP Warning:  The use statement with non-compound name 'Throwable' has no effect in /app/vendor/laravel/octane/bin/frankenphp-worker.php on line 9
      WARN  PHP Warning:  The use statement with non-compound name 'Throwable' has no effect in /app/vendor/laravel/octane/bin/frankenphp-worker.php on line 9
      WARN  PHP Warning:  The use statement with non-compound name 'Throwable' has no effect in /app/vendor/laravel/octane/bin/frankenphp-worker.php on line 9
      ...