Bump lxml from 4.3.0 to 4.3.1 (#69)

Bumps [lxml](https://github.com/lxml/lxml) from 4.3.0 to 4.3.1.
- [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-4.3.0...lxml-4.3.1

)

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

requirements.txt

 backports.tempfile==1.0
 futures==3.2.0
 fuzzywuzzy==0.17.0
-lxml==4.3.0
+lxml==4.3.1
 matplotlib==2.2.3
 numpy==1.16.1
 Pillow>=3.4.1