[Pkg-rust-maintainers] Bug#1025617: Bug#1025617: rust-async-io: Please update to v1.12.0

[Peter Green]

 > Please update to v1.12.0.

 From checking upstream git, the only change in 1.12.0 is switching the windows backend from
"winapi" (which is in Debian) to "windows-sys" (which is not in Debian), upstream git
has since switched again and now uses rustix on all platforms.

I could make a patch to strip out the windows-sys support and upload 1.12.0 to Debian
but it seems a bit of a pointless excersize to make such a patch only to drop it again
when 1.13 is released.