Bump unstructured from 0.15.13 to 0.16.6

Bumps [unstructured](https://github.com/Unstructured-IO/unstructured) from 0.15.13 to 0.16.6.
- [Release notes](https://github.com/Unstructured-IO/unstructured/releases)
- [Changelog](https://github.com/Unstructured-IO/unstructured/blob/main/CHANGELOG.md)
- [Commits](Unstructured-IO/unstructured@0.15.13...0.16.6)

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

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

requirements.txt

@@ -37,4 +37,4 @@ textdistance==4.6.3
 tiktoken==0.7.0
 tqdm==4.66.5
 umap-learn==0.5.6
-unstructured==0.15.13
+unstructured==0.16.6