[2.3] php8.1 selfupdate error when no old files exist

[it-can]

I get this error after a fresh install on my mac machine with php8.1, I run this command

composer self-update --clean-backups

You are already using the latest available Composer version 2.3.3 (stable channel).

In SelfUpdateCommand.php line 491:

  [TypeError]
  Composer\Command\SelfUpdateCommand::cleanBackups(): Argument #2 ($except) must be of type
   ?string, bool given, called in phar:///usr/local/bin/composer/src/Composer/Command/SelfU
  pdateCommand.php on line 215


Exception trace:
  at phar:///usr/local/bin/composer/src/Composer/Command/SelfUpdateCommand.php:491
 Composer\Command\SelfUpdateCommand->cleanBackups() at phar:///usr/local/bin/composer/src/Composer/Command/SelfUpdateCommand.php:215
 Composer\Command\SelfUpdateCommand->execute() at phar:///usr/local/bin/composer/vendor/symfony/console/Command/Command.php:298
 Symfony\Component\Console\Command\Command->run() at phar:///usr/local/bin/composer/vendor/symfony/console/Application.php:1015
 Symfony\Component\Console\Application->doRunCommand() at phar:///usr/local/bin/composer/vendor/symfony/console/Application.php:299
 Symfony\Component\Console\Application->doRun() at phar:///usr/local/bin/composer/src/Composer/Console/Application.php:334
 Composer\Console\Application->doRun() at phar:///usr/local/bin/composer/vendor/symfony/console/Application.php:171
 Symfony\Component\Console\Application->run() at phar:///usr/local/bin/composer/src/Composer/Console/Application.php:130
 Composer\Console\Application->run() at phar:///usr/local/bin/composer/bin/composer:83
 require() at /usr/local/bin/composer:29

The problem is caused by this function

composer/src/Composer/Command/SelfUpdateCommand.php

Line 491 in dce63fd

protected function cleanBackups(string $rollbackDir, ?string $except = null): void

cleanBackups(string $rollbackDir, ?string $except = null): void

$except is excpected to be a string, but a boolean will be passed if there are no backup files available... See function getLastBackupVersion

composer/src/Composer/Command/SelfUpdateCommand.php

Line 511 in dce63fd

protected function getLastBackupVersion(string $rollbackDir)

This function will return false when there are no old backups...

I created a PR #10704