hard-xml-derive: create an upstream pull request for with attribute

[dongsupark]

ue-rs has several 3rd-party patches under vendor/hard-xml-derive to add with attributes.

Ideally the changes should be created as an upstream pull request of the upstream repo.

[dongsupark]

Created an upstream PR https://gitlab.com/kevincox/hard-xml/-/merge_requests/13.

[dongsupark]

The upstream PR https://gitlab.com/kevincox/hard-xml/-/merge_requests/13 was merged, and included in hard-xml v1.34.0. We need to also update the corresponding ue-rs code.

[pothos]

Should we open a new issue for the remaining task?

[dongsupark]

Right, sorry, I still have to get back to the rest work.