Bug#1033334: Don't include in Bookworm

[Moritz Muehlenhoff]

Source: rust-boxfnonce
Version: 0.1.1-2
Severity: serious

Per https://rustsec.org/advisories/RUSTSEC-2019-0040.html rust-boxfnonce is 
obsolete,
let's keep it out of bookworm (and remove from the archive).

Cheers,
        Moritz