Update code for PHP 8.4 and replace abandoned dependency

[skyler544]

Thanks for the great blog post!

I'm using PHP 8.4 and found that I only needed to make minor changes to get the code working:

1. Update laminas/laminas-diactoros:

composer require laminas/laminas-diactoros:^3.8 --with-all-dependencies

2. Replace narrowspark/http-emitter (abandoned, not installable with PHP 8.4):

composer require laminas/laminas-httphandlerrunner
composer remove narrowspark/http-emitter