chore(deps): bump unstructured from 0.15.12 to 0.16.15

Bumps [unstructured](https://github.com/Unstructured-IO/unstructured) from 0.15.12 to 0.16.15.
- [Release notes](https://github.com/Unstructured-IO/unstructured/releases)
- [Changelog](https://github.com/Unstructured-IO/unstructured/blob/main/CHANGELOG.md)
- [Commits](Unstructured-IO/unstructured@0.15.12...0.16.15)

---
updated-dependencies:
- dependency-name: unstructured
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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