upgrade requests

Author: drazisil

requirements/dev.txt

@@ -4,6 +4,6 @@ Pygments==2.2.0
 colorama==0.3.9
 coverage==4.4.1
 httpie==0.9.9
-requests==2.18.4
+requests==2.20.0
 selenium==3.5.0
 unittest-xml-reporting==2.1.0