Upgrade markupsafe to fix setuptools error

ImportError: cannot import name 'Feature' from 'setuptools'

Setuptools 46 introduced a breaking change and removed Feature support
pypa/setuptools#1979

Fixed in pallets/markupsafe#24

Author: ltvolks

requirements.txt

@@ -13,7 +13,7 @@ idna==2.7
 imagesize==1.1.0
 jinja2==2.10.1
 markdown==3.0.1
-markupsafe==1.0
+markupsafe==1.1.1
 packaging==18.0
 pandoc==1.0.2
 pbr==5.1.0