Deprecation warnings when running with PHP 8.1

[kdambekalns]

When using this with PHP 8.1 (or higher), you run into some warnings like this:

$ ./bin/neoscs DistributionPackages
PHP Deprecated:  Return type of Vette\Neos\CodeStyle\Packages\PackageCollection::key() should
either be compatible with Iterator::key(): mixed, or the #[\ReturnTypeWillChange] attribute should be
used to temporarily suppress the notice in /…/Packages/Libraries/cvette/neos-code-style/src/Packages
/PackageCollection.php on line 91