rB8e21d528cab98 neglected to add versioning to add the new
"use_attribute" and "attribute_name" properties to the modifier input
list. Though they are added if the modifier's interface is updated, that
doesn't happen when the file is loaded, so patch adds them manually.
Another solution would be calling `MOD_nodes_update_interface`,
but that would require including the modifiers module.
Differential Revision: https://developer.blender.org/D12535
b37d36a60f