Bump lxml from 4.5.0 to 4.5.1

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](lxml/lxml@lxml-4.5.0...lxml-4.5.1)

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

Author: dependabot-preview[bot]

requirements.txt

@@ -6,7 +6,7 @@ colorful==0.5.4
 filetype==1.0.7
 junit-xml==1.9
 emoji==0.5.4
-lxml==4.5.0
+lxml==4.5.1
 ddt==1.4.0
 pytest==5.4.2
 nose==1.3.7