Bump cross-spawn in /samples/react-pnp-js-sample

Bumps  and [cross-spawn](https://github.com/moxystudio/node-cross-spawn). These dependencies needed to be updated together.

Updates `cross-spawn` from 7.0.3 to 7.0.6
- [Changelog](https://github.com/moxystudio/node-cross-spawn/blob/master/CHANGELOG.md)
- [Commits](moxystudio/node-cross-spawn@v7.0.3...v7.0.6)

Updates `cross-spawn` from 6.0.5 to 7.0.6
- [Changelog](https://github.com/moxystudio/node-cross-spawn/blob/master/CHANGELOG.md)
- [Commits](moxystudio/node-cross-spawn@v7.0.3...v7.0.6)

---
updated-dependencies:
- dependency-name: cross-spawn
  dependency-type: indirect
- dependency-name: cross-spawn
  dependency-type: indirect
...

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

Author: dependabot[bot]