Bump lettre from 0.11.6 to 0.11.7

Bumps [lettre](https://github.com/lettre/lettre) from 0.11.6 to 0.11.7.
- [Release notes](https://github.com/lettre/lettre/releases)
- [Changelog](https://github.com/lettre/lettre/blob/master/CHANGELOG.md)
- [Commits](lettre/lettre@v0.11.6...v0.11.7)

---
updated-dependencies:
- dependency-name: lettre
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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