Bump semver and cross-spawn

Removes [semver](https://github.com/npm/node-semver). It's no longer used after updating ancestor dependency [cross-spawn](https://github.com/moxystudio/node-cross-spawn). These dependencies need to be updated together.


Removes `semver`

Updates `cross-spawn` from 6.0.5 to 7.0.3
- [Changelog](https://github.com/moxystudio/node-cross-spawn/blob/master/CHANGELOG.md)
- [Commits](moxystudio/node-cross-spawn@v6.0.5...v7.0.3)

---
updated-dependencies:
- dependency-name: semver
  dependency-type: indirect
- dependency-name: cross-spawn
  dependency-type: direct:production
...

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