chore(deps-dev): bump lxml from 5.3.0 to 5.3.1 in /backend

Bumps [lxml](https://github.com/lxml/lxml) from 5.3.0 to 5.3.1.
- [Release notes](https://github.com/lxml/lxml/releases)
- [Changelog](https://github.com/lxml/lxml/blob/master/CHANGES.txt)
- [Commits](lxml/lxml@lxml-5.3.0...lxml-5.3.1)

---
updated-dependencies:
- dependency-name: lxml
  dependency-type: direct:development
  update-type: version-update:semver-patch
...

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