rust-hg-core: upgrade dependencies This upgrades all dependencies to their latest version, except `clap` and `zstd` whose latest versions do not support our minimum supported Rust version 1.48.0. Same as for `rhg`, it contains security fix for `regex` which does not affect us too much, but doesn't hurt, and the rest of the upgrades are there simply to keep up. Differential Revision: https://phab.mercurial-scm.org/D12358