Bump lxml from 4.5.2 to 4.6.2

Bumps [lxml](https://github.com/lxml/lxml) from 4.5.2 to 4.6.2.
- [Release notes](https://github.com/lxml/lxml/releases)
- [Changelog](https://github.com/lxml/lxml/blob/master/CHANGES.txt)
- [Commits](lxml/lxml@lxml-4.5.2...lxml-4.6.2)

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

Diff for: requirements.txt

@@ -1,5 +1,5 @@
 argparse==1.2.1
 libarchive-c==2.9
-lxml==4.5.2
+lxml==4.6.2
 psycopg2-binary==2.8.4
 six==1.10.0