Bump lxml from 4.4.0 to 4.6.2

Bumps [lxml](https://github.com/lxml/lxml) from 4.4.0 to 4.6.2.
- [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-4.4.0...lxml-4.6.2)

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

requirements.txt

@@ -9,7 +9,7 @@ chardet==3.0.4
 clint==0.5.1
 docutils==0.14
 idna==2.8
-lxml==4.4.0
+lxml==4.6.2
 pendulum==2.0.5
 pkginfo==1.5.0.1
 progressbar==2.5