Migrate to PHP 8 - PHP 7 unmaintained

[DjordyKoert]

Support for PHP 7.4 has stopped 9 months ago. NelmioApiDocBundle still supports PHP 7.2 and higher so it's probably a good idea to migrate to PHP 8 and Symfony 6 since Symfony 6 only supports PHP 8.0.2 or higher.

This would also improve maintainability of this project since backwards compatibility with older PHP versions (read PHP 7) wouldn't need to be kept in mind.

Thoughts?

[GuilhemN]

I'm not sure, as long as we don't have a specific new feature or fix where using PHP 8 would help significantly I prefer not to change the constraint. It's not a very big deal on our side I think, and if it can help some developers maintain NelmioApiDocBundle up to date I think it's worth it.

[DjordyKoert]

Well yeah for now it doesn't look like PHP 8 is needed to be able to bring specific feature/fix to NelmioApiDocBundle, the main thing it would do is ease maintenance of this package as far as I can tell.

It could for example remove some boilerplate code because of the introduction of promoted constructor properties.