converted authentication test asserts to pytest

Updated Link ti Django Docs

The Url to the settings/#caches Link changed in Django documentation.

Just makes the topic page easier to find.

Closes #1673

converted descriptions and ecoders test asserts to pytest

converted asserts of atomic requests and decorators tests to pytest

converted test asserts of generics-test to pytest

typo

As of PR #4377, `max_digits=None` is allowed for `DecimalField`.

converted generic relations assert to pytest style

Remove unnecessary "a"

docs: grammar fix