[php] PHP 8.0 end of life

[ybelenko]

Here we go again
PHP 8.0 reached end of life at 26 Nov 2023

End of life - A release that is no longer supported. Users of this release should upgrade as soon as possible, as they may be exposed to unpatched security vulnerabilities.

PHP: Supported Versions:

• 8.0 until 26 Nov 2023
• 8.1 until 26 Nov 2024
• 8.2 until 8 Dec 2025

It seems that we need to change minimum PHP version to php: ^8.1 in all php generators. We should not only change composer requirement, but check with extra caution that Composer actually can resolve all the deps under PHP 8.1. In other words check that generator builds and actually works.

Current Requirements:

Generator	PHP version
php client	^7.4 || ^8.0
Laravel server	>= 7.2.5
Lumen server	>= 7.2.5
Slim4 server	^7.4 || ^8.0
Symfony server	>=7.4.0|>=8.0.2
php-mezzio-ph server	^ 7.3 || ^8.0
php-mezzio-ph-modern server	^8.0
php-dt client	^7.3 || ^8.0
php-dt-modern client	^8.0

cc @jebentier @dkarlovi @mandrean @jfastnacht @renepardon
cc @Articus as author of php-mezzio-ph, php-mezzio-ph-modern, php-dt client, php-dt-modern client

[loicconan]

Done on Symfony server : #18357