robo(deps): bump structopt from 0.3.25 to 0.3.26

Bumps [structopt](https://github.com/TeXitoi/structopt) from 0.3.25 to 0.3.26.
- [Release notes](https://github.com/TeXitoi/structopt/releases)
- [Changelog](https://github.com/TeXitoi/structopt/blob/master/CHANGELOG.md)
- [Commits](TeXitoi/structopt@v0.3.25...v0.3.26)

---
updated-dependencies:
- dependency-name: structopt
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <support@github.com>