Bump lxml from 4.2.3 to 4.2.4

Bumps [lxml](https://github.com/lxml/lxml) from 4.2.3 to 4.2.4.
- [Release notes](https://github.com/lxml/lxml/releases)
- [Changelog](https://github.com/lxml/lxml/blob/master/CHANGES.txt)
- [Commits](lxml/lxml@lxml-4.2.3...lxml-4.2.4)

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

Author: dependabot-support

requirements.txt

@@ -6,7 +6,7 @@ geoip2==2.9.0
 git+https://github.com/CloudBotIRC/mcstatus.git@master
 imgurpython==1.1.7
 isodate==0.6.0
-lxml==4.2.3
+lxml==4.2.4
 microdata==0.6.1
 nltk==3.2.5
 psutil==5.4.6