Use the latest version of sorl-thumbnail

requirements.txt

-Django==1.11
-djangorestframework==3.6.2
-django-extensions==1.7.8
+Django==1.11.2
+djangorestframework==3.6.3
+django-extensions==1.7.9
 django-imagekit==4.0
 django-taggit==0.22.0
 django-und
@@ -12,4 +12,4 @@ django-allauth
 django-fsm
 django-markdown2
 url
-sorl-thumbnail
+-e git+https://github.com/mariocesar/sorl-thumbnail.git#egg=sorl-thumbnail