[upd] pypi: Bump lxml from 5.3.2 to 5.4.0

Bumps [lxml](https://github.com/lxml/lxml) from 5.3.2 to 5.4.0.
- [Release notes](https://github.com/lxml/lxml/releases)
- [Changelog](https://github.com/lxml/lxml/blob/master/CHANGES.txt)
- [Commits](https://github.com/lxml/lxml/compare/lxml-5.3.2...lxml-5.4.0)

---
updated-dependencies:
- dependency-name: lxml
  dependency-version: 5.4.0
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

requirements.txt

@@ -3,7 +3,7 @@ babel==2.17.0
 flask-babel==4.0.0
 flask==3.1.0
 jinja2==3.1.6
-lxml==5.3.2
+lxml==5.4.0
 pygments==2.19.1
 python-dateutil==2.9.0.post0
 pyyaml==6.0.2