Bump mongoose from 5.12.2 to 5.13.6

Bumps [mongoose](https://github.com/Automattic/mongoose) from 5.12.2 to 5.13.6.
- [Release notes](https://github.com/Automattic/mongoose/releases)
- [Changelog](https://github.com/Automattic/mongoose/blob/master/History.md)
- [Commits](https://github.com/Automattic/mongoose/commits)

---
updated-dependencies:
- dependency-name: mongoose
  dependency-type: direct:development
  update-type: version-update:semver-minor
...

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

Author: dependabot[bot]