Switch from October to Winter - Composer update doesn't start

[m-paniez9292]

Winter CMS Build

Other (please specify below)

PHP Version

8.0

Database engine

MySQL/MariaDB

Plugins installed

No response

Issue description

Hi all,
We have a little website on October and would use it to test the switch method to Winter.
The October version is 473 and we put composer.json to use the "Wizard Method Installation" switch method describe on https://wintercms.com/blog/post/how-start-using-winter-cms .
Composer version is 1
When we put "composer update", we have :

PHP Fatal error:  Uncaught ArgumentCountError: array_merge() does not accept unknown named parameters in /usr/share/php/Composer/DependencyResolver/DefaultPolicy.php:84

Stack trace:
#0 [internal function]: array_merge()
#1 /usr/share/php/Composer/DependencyResolver/DefaultPolicy.php(84): call_user_func_array()
#2 /usr/share/php/Composer/DependencyResolver/Solver.php(387): Composer\DependencyResolver\DefaultPolicy->selectPreferredPackages()
#3 /usr/share/php/Composer/DependencyResolver/Solver.php(742): Composer\DependencyResolver\Solver->selectAndInstall()
#4 /usr/share/php/Composer/DependencyResolver/Solver.php(231): Composer\DependencyResolver\Solver->runSat()
#5 /usr/share/php/Composer/Installer.php(475): Composer\DependencyResolver\Solver->solve()
#6 /usr/share/php/Composer/Installer.php(229): Composer\Installer->doInstall()
#7 /usr/share/php/Composer/Command/UpdateCommand.php(162): Composer\Installer->run()
#8 /usr/share/php/Symfony/Component/Console/Command/Command.php(255): Composer\Command\UpdateCommand->execute()
#9 /usr/share/php/Symfony/Component/Console/Application.php(953): Symfony\Component\Console\Command\Command->run()
#10 /usr/share/php/Symfony/Component/Console/Application.php(248): Symfony\Component\Console\Application->doRunCommand()
#11 /usr/share/php/Composer/Console/Application.php(258): Symfony\Component\Console\Application->doRun()
#12 /usr/share/php/Symfony/Component/Console/Application.php(148): Composer\Console\Application->doRun()
#13 /usr/share/php/Composer/Console/Application.php(104): Symfony\Component\Console\Application->run()
#14 /usr/bin/composer(57): Composer\Console\Application->run()
#15 {main}
  thrown in /usr/share/php/Composer/DependencyResolver/DefaultPolicy.php on line 84

Thanks

Steps to replicate

This website is recent (3 month ago) and it has only 1 page.
We just copy-paste your composer.json and run composer update

Workaround

EDIT : Upgrade Composer v1 to v2 solve that problem