Dependencies: don't override `get_available_name` (Django Storages)
The fuction `get_available_overwrite_name` was removed.
There is a setting `file_overwrite` which is set to `True` by default and our
override shouldn't be required anymore.
https://django-storages.readthedocs.io/en/latest/backends/amazon-S3.html#settings
Related: https://github.com/readthedocs/readthedocs.org/pull/11502