[Security] Bump lxml from 4.5.2 to 4.6.3 in /src/requirements

Bumps [lxml](https://github.com/lxml/lxml) from 4.5.2 to 4.6.3. **This update includes security fixes.**
- [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-4.5.2...lxml-4.6.3)

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

src/requirements/production.txt

@@ -25,7 +25,7 @@ html5lib==1.1
 icalendar==4.0.6
 ipython==7.18.1
 irc3==1.1.6
-lxml==4.5.2
+lxml==4.6.3
 olefile==0.46
 pipdeptree==1.0.0
 psycopg2-binary==2.8.5