www/py-django-{dj21,dj22}-cors-headers: Update to 3.2.0

Notable changes since 3.0.2:

• Drop Python 2 support, only Python 3.5-3.8 is supported now.
• Support the value "file://" for origins, which is accidentally sent by some versions of Chrome on Android.

https://github.com/adamchainz/django-cors-headers/blob/3.2.0/HISTORY.rst