RegistryImportedFeed::setAssetHandler() Filesystem::addPlugin() no longer works

[emteknetnz]

https://github.com/silverstripe/silverstripe-registry/actions/runs/3645212467/jobs/6155159276

1) SilverStripe\Registry\Tests\RegistryImportFeedControllerTest::testNonExistentClassInLatestFeedReturnsNotFound
Error: Call to undefined method SilverStripe\Assets\Flysystem\Filesystem::addPlugin()

/home/runner/work/silverstripe-registry/silverstripe-registry/src/RegistryImportFeed.php:83
/home/runner/work/silverstripe-registry/silverstripe-registry/vendor/silverstripe/framework/src/Core/Injector/Injector.php:848
/home/runner/work/silverstripe-registry/silverstripe-registry/vendor/silverstripe/framework/src/Core/Injector/Injector.php:692
/home/runner/work/silverstripe-registry/silverstripe-registry/vendor/silverstripe/framework/src/Core/Injector/Injector.php:661
/home/runner/work/silverstripe-registry/silverstripe-registry/vendor/silverstripe/framework/src/Core/Injector/Injector.php:1029
/home/runner/work/silverstripe-registry/silverstripe-registry/vendor/silverstripe/framework/src/Core/Injector/Injector.php:982
/home/runner/work/silverstripe-registry/silverstripe-registry/vendor/silverstripe/framework/src/Core/Injector/Injector.php:1152
/home/runner/work/silverstripe-registry/silverstripe-registry/vendor/silverstripe/framework/src/Core/Injector/Injectable.php:30
/home/runner/work/silverstripe-registry/silverstripe-registry/tests/RegistryImportFeedTest.php:21

$handler->getFilesystem()->addPlugin(new ListFiles);

https://github.com/silverstripe/silverstripe-registry/blob/3/src/RegistryImportFeed.php#L83

This probably broke as part of the CMS 5 flysystem upgrade

I'm not sure what "ListFiles" does, if we just delete this line we may lose functionality here, though I'm not sure