[12.x] fix: add polyfill requirement to illuminate packages

[erikgaal]

After the introduction of #56706, we need to make the individual illuminate/* packages also have the requirement for symfony/polyfill-php85.

This prevents the following error from happening if you only use separate illuminate/support package:

PHP Fatal error:  Uncaught Error: Call to undefined function Illuminate\Support\array_first() in /home/runner/.composer/vendor/illuminate/collections/Arr.php:260
Stack trace:
#0 /home/runner/.composer/vendor/illuminate/collections/Collection.php(432): Illuminate\Support\Arr::first()
#1 /home/runner/.composer/vendor/erikgaal/cx/src/Tasks/Renderer/StaticRenderer.php(26): Illuminate\Support\Collection->first()
#2 /home/runner/.composer/vendor/erikgaal/cx/src/Tasks/TaskRunner.php(33): Cx\Tasks\Renderer\StaticRenderer->started()
#3 /home/runner/.composer/vendor/erikgaal/cx/src/Commands/RunManyCommand.php(53): Cx\Tasks\TaskRunner->run()
#4 /home/runner/.composer/vendor/symfony/console/Command/Command.php(318): Cx\Commands\RunManyCommand->execute()
#5 /home/runner/.composer/vendor/symfony/console/Application.php(1074): Symfony\Component\Console\Command\Command->run()
#6 /home/runner/.composer/vendor/symfony/console/Application.php(341): Symfony\Component\Console\Application->doRunCommand()
#7 /home/runner/.composer/vendor/symfony/console/Application.php(192): Symfony\Component\Console\Application->doRun()
#8 /home/runner/.composer/vendor/erikgaal/cx/cx(36): Symfony\Component\Console\Application->run()
#9 /home/runner/.composer/vendor/bin/cx(119): include('...')

[erikgaal]

Thanks @taylorotwell!