Auto merge of #3634 - steveklabnik:bump-semver, r=alexcrichton

bump semver version

Thanks to @raphlinus , semver-parser no longer depends on regex. The code is (probably, I haven't technically tested it but it's hard to imagine it's not) faster, smaller, and has zero dependencies, as well as better errors.

This new version of semver only updates the dependencies involved, no interface changes, so it should be a drop-in replacement.