Bump lxml from 4.6.2 to 4.6.3

Bumps [lxml](https://github.com/lxml/lxml) from 4.6.2 to 4.6.3.
- [Release notes](https://github.com/lxml/lxml/releases)
- [Changelog](https://github.com/lxml/lxml/blob/master/CHANGES.txt)
- [Commits](lxml/lxml@lxml-4.6.2...lxml-4.6.3)

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

requirements.txt

@@ -3,7 +3,7 @@ chardet==4.0.0
 idna==3.1
 Jinja2==2.11.3
 kinto-http==10.7.0
-lxml==4.6.2
+lxml==4.6.3
 MarkupSafe==1.1.1
 python-dateutil==2.8.1
 requests==2.25.1