Fix fleeting install subcommand for Windows
What does this MR do?
Fix fleeting install subcommand for Windows
Plugin installation was not working on Windows due to plugins having a different path for it to also be compatible as a Windows container.
The fleeting-artifact library fixes this, so we just need to update for the fix (gitlab-org/fleeting/fleeting-artifact!1 (merged)).
Why was this MR needed?
Plugin installation on Windows would complain with file in archive was not in 'plugin' dir.
What's the best way to test this MR?
gitlab-runner fleeting install will now function correctly on Windows.