Bug#976434: [cargo] please update to v1.44+

[Lyndon Brown]

Package: cargo
Version: 0.43.1-4

Please can cargo be updated to v1.44 (0.46). It would be nice to be
able to make use of `cargo tree`.

Thanks for getting rustc updated the other day to 1.48 which means I
can play with intra-doc-links. :D