Use Django-Storages with IAM Instance Profiles
The docs now explain this:

If AWS_ACCESS_KEY_ID and AWS_SECRET_ACCESS_KEY are not set, boto3 internally looks up IAM credentials.
Django-Storages provides an S3 file storage backend for Django.  It lists
AWS_ACCESS_KEY_ID and AWS_SECRET_ACCESS_KEY as required settings.  If I am using an AWS Instance Profile to provide S3 access instead of a key pair, how do I configure Django-Storages?