Update structopt-derive requirement from 0.2.9 to 0.3.0
Update structopt-derive requirement from 0.2.9 to 0.3.0

Updates the requirements on [structopt-derive](https://github.com/TeXitoi/structopt) to permit the latest version.
- [Release notes](https://github.com/TeXitoi/structopt/releases)
- [Changelog](https://github.com/TeXitoi/structopt/blob/master/CHANGELOG.md)
- [Commits](https://github.com/TeXitoi/structopt/compare/v0.2.9...v0.3.0)

Signed-off-by: dependabot-preview[bot] <5bdcd3c0d4d24ae3e71b3b452a024c6324c7e4bb@dependabot.com>
CryZe/livesplit-core,CryZe/livesplit-core