Bump lxml from 4.8.0 to 4.9.1

Bumps [lxml](https://github.com/lxml/lxml) from 4.8.0 to 4.9.1.
- [Release notes](https://github.com/lxml/lxml/releases)
- [Changelog](https://github.com/lxml/lxml/blob/master/CHANGES.txt)
- [Commits](lxml/lxml@lxml-4.8.0...lxml-4.9.1)

---
updated-dependencies:
- dependency-name: lxml
  dependency-type: direct:production
...

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

Author: dependabot[bot]

requirements.txt

@@ -35,7 +35,7 @@ javaproperties==0.8.1
 Jinja2==3.0.3
 jsonstreams==0.6.0
 license-expression==21.6.14
-lxml==4.8.0
+lxml==4.9.1
 MarkupSafe==2.0.1
 more-itertools==8.13.0
 normality==2.3.3