Log Message:
py-django-cors-headers: updated to 3.1.1

3.1.1:
Support the value file:// for origins, which is accidentally sent by some \ 
versions of Chrome on Android.

3.1.0:
Drop Python 2 support, only Python 3.5-3.7 is supported now.
Fix all links for move from github.com/ottoyiu/django-cors-headers to \ 
github.com/adamchainz/django-cors-headers.