Update django-cors-headers from 2.5.2 to 3.0.2

Author: pyup-bot

requirements.txt

@@ -6,7 +6,7 @@ django-allauth==0.39.1
 django-compressor==2.2
 django-htmlmin==0.11.0
 django-storages==1.7.1
-django-cors-headers==2.5.2
+django-cors-headers==3.0.2
 djangorestframework==3.9.2
 django-rest-auth==0.9.5
 furl==2.0.0