build(deps): bump unstructured in the pip group across 1 directory

Bumps the pip group with 1 update in the / directory: [unstructured](https://github.com/Unstructured-IO/unstructured).


Updates `unstructured` from 0.16.9 to 0.18.18
- [Release notes](https://github.com/Unstructured-IO/unstructured/releases)
- [Changelog](https://github.com/Unstructured-IO/unstructured/blob/main/CHANGELOG.md)
- [Commits](Unstructured-IO/unstructured@0.16.9...0.18.18)

---
updated-dependencies:
- dependency-name: unstructured
  dependency-version: 0.18.18
  dependency-type: direct:production
  dependency-group: pip
...

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

Author: dependabot[bot]

requirements.txt

@@ -11,4 +11,4 @@ python-docx==1.1.2
 openpyxl==3.1.5
 pandas==2.2.3
 chromadb==0.4.24
-unstructured==0.16.9
+unstructured==0.18.18