build(deps): bump nodemailer and loopback

Bumps [nodemailer](https://github.com/nodemailer/nodemailer) to 6.9.1 and updates ancestor dependency [loopback](https://github.com/strongloop/loopback). These dependencies need to be updated together.


Updates `nodemailer` from 2.7.2 to 6.9.1
- [Release notes](https://github.com/nodemailer/nodemailer/releases)
- [Changelog](https://github.com/nodemailer/nodemailer/blob/master/CHANGELOG.md)
- [Commits](nodemailer/nodemailer@v2.7.2...v6.9.1)

Updates `loopback` from 2.42.0 to 3.28.0
- [Release notes](https://github.com/strongloop/loopback/releases)
- [Changelog](https://github.com/strongloop/loopback/blob/master/CHANGES.md)
- [Commits](strongloop/loopback@v2.42.0...v3.28.0)

---
updated-dependencies:
- dependency-name: nodemailer
  dependency-type: indirect
- dependency-name: loopback
  dependency-type: direct:development
...

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