Django 4.2 no longer supports the DEFAULT_FILE_STORAGE setting, and we

hadn't updated our code to move fully over to STORAGES. This prevented

us from properly storing or accessing files via S3 (in the case of

reviews.reviewboard.org), and would have affected users using this or

other storage backends.
We now set STORAGES['default'] instead, which is the modern

equivalent.
The django-storages dependency has been bumped as part of this, as older

releases don't work with Django 4.2. There have been some changes in

modern django-storages, which impacted some of our loading code. That

code has been updated accordingly.
As django-storages is now light-weight, with all the requirements for

services like S3 being available via "extra" dependencies, we can now

depend on it unconditionally. Our S3 support in ReviewBoard[s3] now

just wraps django-storages[s3]. Of note, they now use boto3, as

opposed to the old boto we used before.
One notable change is that it appears django-storages before may have

given us signed URLs unconditionally. It's not entirely clear, but it

does seem that we aren't getting signed URLs anymore due to the

aws_querystring_auth setting we pass in. We had this set to False,

which is a bad default. We now set it to True and set a standard

expiration for signed URLs.
One last semi-related thing is that we had a bad field name set in the

configuration form that prevented the configured storage backend from

being selected by default. This has been corrected.
Semi-related, the support for CouchDB is now explicitly turned off. It

turns out we haven't actually worked with it in ages, and we never

offered native configuration. It's doubtful anyone's used it since its

introduction, and isn't worth putting in the release notes.

Unit tests pass.
Re-deployed and verified that file storage and access worked again.