require jinja to have unique function

requirements.txt

@@ -3,6 +3,7 @@ flask==1.0.2
 flask-babel==0.11.2
 lxml==4.2.3
 idna==2.7
+jinja2==2.10
 pygments==2.1.3
 pyopenssl==18.0.0
 python-dateutil==2.7.3