Bump lxml from 4.5.0 to 4.5.1 in /src/requirements (#540)

Bumps [lxml](https://github.com/lxml/lxml) from 4.5.0 to 4.5.1.
- [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-4.5.0...lxml-4.5.1)

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Co-authored-by: dependabot-preview[bot] <27856297+dependabot-preview[bot]@users.noreply.github.com>

src/requirements/production.txt

@@ -22,7 +22,7 @@ html5lib==1.0.1
 icalendar==4.0.6
 ipython==7.15.0
 irc3==1.1.5
-lxml==4.5.0
+lxml==4.5.1
 olefile==0.46
 Pillow==7.1.2
 pipdeptree==0.13.2