Update lxml from 4.1.1 to 4.5.2
diff --git a/css/requirements.txt b/css/requirements.txt
index a008e3e..725ddd9 100644
--- a/css/requirements.txt
+++ b/css/requirements.txt
@@ -1,6 +1,6 @@
 Template-Python==0.1.post1
 html5lib==1.1
-lxml==4.1.1
+lxml==4.5.2
 mercurial==4.5
 six==1.15.0
 webencodings==0.5.1