Bump trix from 2.1.15 to 2.1.16 (#2962)

Bumps [trix](https://github.com/basecamp/trix) from 2.1.15 to 2.1.16.
- [Release notes](https://github.com/basecamp/trix/releases)
- [Commits](basecamp/trix@v2.1.15...v2.1.16)

---
updated-dependencies:
- dependency-name: trix
  dependency-version: 2.1.16
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]