build(deps): bump diesel from 2.1.5 to 2.1.6

Bumps [diesel](https://github.com/diesel-rs/diesel) from 2.1.5 to 2.1.6.
- [Release notes](https://github.com/diesel-rs/diesel/releases)
- [Changelog](https://github.com/diesel-rs/diesel/blob/v2.1.6/CHANGELOG.md)
- [Commits](diesel-rs/diesel@v2.1.5...v2.1.6)

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

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