Bug#1049413: librsvg: Update to 2.56 or later

[Simon McVittie]

On Tue, 15 Aug 2023 at 08:25:55 -0400, Jeremy Bícha wrote:
> It would be nice if we updated librsvg to 2.56 (GNOME 44 series) or
> 2.58 (GNOME 45 series).

Are you sure you mean 2.58? https://gitlab.gnome.org/GNOME/librsvg seems
to be version 2.56.92 right now, which suggests that GNOME 45 will have
librsvg 2.57.x.

Upstream documentation says:

    Before version 2.55.x, librsvg's versioning scheme was such that a
    release with an even minor number was considered a stable release
    suitable for production use (e.g. 2.54.x), and an odd minor number
    was a development release only.

    Starting with 2.55.x, all minor numbers are considered
    stable. Development and beta versions have a micro version
    starting at 90 (e.g. 2.55.90)

    — https://gitlab.gnome.org/GNOME/librsvg/-/blob/main/devel-docs/security.rst

so maybe we can at least go to 2.55.x, even if moving beyond there is
not feasible right now?

> But 2.56 drops the vendored Rust crate dependencies, forcing us to
> either revendor librsvg or use the Debian packaged crates.

I don't know Rust or cargo, so I am not going to be able to help with
this.

    smcv