Use dependencies from git when building locally

Use dependencies from git when building locally

Specifying a version number for dependencies prevents building against
recent changes upstream. However, either `path` or `git` can be given to
be used locally while `version` is still used when publishing to a
registry like crates.io. For details, see:

https://doc.rust-lang.org/cargo/reference/specifying-dependencies.html#multiple-locations