Bump lxml from 4.6.3 to 4.6.5

Bumps [lxml](https://github.com/lxml/lxml) from 4.6.3 to 4.6.5.
- [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-4.6.3...lxml-4.6.5)

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

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

requirements.lock.txt

@@ -38,7 +38,7 @@ iniconfig==1.1.1
 itsdangerous==1.1.0
 Jinja2==2.11.3
 kombu==5.0.2
-lxml==4.6.3
+lxml==4.6.5
 Mako==1.1.4
 Markdown==3.3.3
 MarkupSafe==1.1.1