⬆️ Bump mongoose from 4.12.3 to 5.6.4

Bumps [mongoose](https://github.com/Automattic/mongoose) from 4.12.3 to 5.6.4.
- [Release notes](https://github.com/Automattic/mongoose/releases)
- [Changelog](https://github.com/Automattic/mongoose/blob/master/History.md)
- [Commits](Automattic/mongoose@4.12.3...5.6.4)

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

Author: dependabot-preview[bot]