No way to respect PHP version requirements when only-best-candidates set to true

[winiarekk]

Is your feature request related to a problem? Please describe.
It seems that there is no way to configure satis to build repository working for given PHP version if only-best-candidates is set to true.

For example if we have an environment running PHP 7.3 and we want to use "friendsofphp/php-cs-fixer": "2.18.1", which is compatible with php: ^5.6 || ^7.0 || ^8.0, setting the flag only-best-candidates to true will cause building a repo with some of the dependencies that are compatible only with PHP 8 (for example "symfony/string": "v6.0.2").

Then, if we try to use our satis repository in the application, composer will fail with the message:

I tried to set desired environment in satis.json file require section, but then building fails with the message:

Describe the solution you'd like
There should be possibility to define desired platform requirement.

Describe alternatives you've considered
Alternatively, setting the flag only-best-candidates to true should result in including best dependency candidate for each PHP version compatible with packages defined in satis.json