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] <[email protected]>

Author: dependabot-preview[bot]

test-requirements.txt

@@ -32,7 +32,7 @@ iniconfig==1.1.1
     # via pytest
 jinja2==2.11.3
     # via sphinx
-lxml==4.6.2
+lxml==4.6.3
     # via -r test-requirements.in
 markupsafe==1.1.1
     # via jinja2