Deprecate the upload command in favor of twine/uv

[messense]

https://docs.pypi.org/attestations/

IMHO implement it in maturin feels like duplicate efforts, what do you think @konstin

[konstin]

uv publish has grown much better in every dimension: More features, better UX, more standards compliant. Remove maturin upload would remove a lot of dependencies. Once uv publish moves out of preview, we can deprecate maturin upload and eventually remove it in maturin 2.0