- switch to PHP 8.3

[krzysztofrewak]

In this PR I switched application to the newest PHP version: 8.3. It includes:

• bumping Dockerfile's PHP versions for development and production environments
• composer dependencies bump
• adding types for all constants in the codebase

Only things I couldn't bump are:

• permission package, but there's a issue for that: Update permissions package #372
• Xdebug stable version, but I decided we can go with that for now, as it's only for development use

Interesting thing:

• tests on my machine on PHP8.3 went green in 105-110s; on 8.2 it was 145s