Update dependencies

[alerque]

This is a follow up to #224 and goes a bit farther updating dependencies.

• The vergen usage was broken before, or at least not working as commented. Supposedly the cargo version was being suppressed when considering a semver, but that wasn't working. It was fixed in a patch version of vergen, and then later changed completely.

  I went with VERGEN_GIT_SEMVER, but if the cargo.toml version field is what you want we can switch to VERGEN_BUILD_SEMVER.