mercurial-core: update Rust version
Our version is old and Debian testing has 1.70.0 now. Let's use it to
unlock some dependencies we need for Mercurial.
This instance will be updated to 18.7.0 (final) on 2021-01-19 at 17:00 UTC+1 (short down time)
Our version is old and Debian testing has 1.70.0 now. Let's use it to
unlock some dependencies we need for Mercurial.