Bump lxml from 4.3.4 to 4.4.0 (#126)

Bumps [lxml](https://github.com/lxml/lxml) from 4.3.4 to 4.4.0.
- [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-4.3.4...lxml-4.4.0

)

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

requirements.txt

@@ -4,7 +4,7 @@ gevent==1.4.0
 gunicorn==19.9.0
 futures
 fuzzywuzzy==0.17.0
-lxml==4.3.4
+lxml==4.4.0
 matplotlib==2.2.4
 numpy==1.16.4
 nltk==3.4.3