Bump semver and mongoose in /examples/gRPC/books

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


Removes `semver`

Updates `mongoose` from 5.11.12 to 5.13.19
- [Release notes](https://github.com/Automattic/mongoose/releases)
- [Changelog](https://github.com/Automattic/mongoose/blob/5.13.19/History.md)
- [Commits](Automattic/mongoose@5.11.12...5.13.19)

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

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]