build(deps): bump mongoose from 5.13.15 to 5.13.20

Bumps [mongoose](https://github.com/Automattic/mongoose) from 5.13.15 to 5.13.20.
- [Release notes](https://github.com/Automattic/mongoose/releases)
- [Changelog](https://github.com/Automattic/mongoose/blob/master/CHANGELOG.md)
- [Commits](Automattic/mongoose@5.13.15...5.13.20)

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

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