Incus: Unbounded YAML Metadata Decode via Parsing

Incus is a system container and virtual machine manager. Prior to version 7.0.0, user provided image and backup tarballs would be unpacked and YAML files parsed without any size restrictions. This was making it easy for an authenticated user to provide a crafted image or backup tarball that when parsed by Incus would lead to a very large YAML document being loaded into memory, potentially causing the entire server to run out of memory. This issue has been patched in version 7.0.0.