librust-libshumate-sys-dev is declared Multi-Arch: same, but fails to
coinstall.

The file /usr/share/cargo/registry/libshumate-sys-0.8.0/GLib-2.0.gir is
shared by librust-libshumate-sys-dev version 0.8.0-1 as present in
forky|unstable with varying content.

Please ensure that shared files have bit-identical content across
architectures, move architecture-dependent files to
architecture-dependent paths or remove the Multi-Arch: same field.

Kind regards

Helmut Grohne