build(deps-dev): bump request-promise from 4.2.5 to 4.2.6

Bumps [request-promise](https://github.com/request/request-promise) from 4.2.5 to 4.2.6.
- [Release notes](https://github.com/request/request-promise/releases)
- [Commits](request/request-promise@v4.2.5...v4.2.6)

---
updated-dependencies:
- dependency-name: request-promise
  dependency-type: direct:development
  update-type: version-update:semver-patch
...

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