[Debian] Hard Rust requirements from May onward

Hi all,

I plan to introduce hard Rust dependencies and Rust code into APT, no earlier than May 2026. This extends at first to the Rust compiler and standard library, and the Sequoia ecosystem.

In particular, our code to parse .deb, .ar, .tar, and the HTTP signature verification code would strongly benefit from memory safe languages and a stronger approach to unit testing.

If you maintain a port without a working Rust toolchain, please ensure it has one within the next 6 months, or sunset the port.

It's important for the project as whole to be able to move forward and rely on modern tools and technologies and not be held back by trying to shoehorn modern software on retro computing devices.

Thank you for your understanding.