Ensured that patching a To-Many relationship correctly raises request error

[sliverc]

Description of the Change

As of DRF upstream change encode/django-rest-framework#9455 our current tests with DRF master are failing. The reason being is that previous to the above change, parser attribute errors would get swallowed.

After this upstream change it occurred that we actually have an error in our code that an attribute error gets hidden and instead of raising a 500-error the code would just continue.

This happened when patching a To-Many relationship with RelationshipView with None. However, the JSON:API spec defines that for emptying a To-Many relationship, caller needs to pass empty array instead of None.

So this PR ensures that when passing on None when patching To-Many relationship, a proper request error (400) is returned instead of 500.

Checklist

• PR only contains one change (considered splitting up PR)
• unit-test added
• documentation updated
• CHANGELOG.md updated (only for user relevant changes)
• author name in AUTHORS

[sliverc]

To see failing drf master tests, go to https://github.com/django-json-api/django-rest-framework-json-api/actions/runs/10648325051/job/29517253464 open Run tox targets and scroll down to drfmaster tests.

These tests have been failing for a while and as we ignore failing drfmaster tests, it is hard to notice it. Possibly have to think about it not to ignore it (as it hardly ever happens that it fails). And if one PR suddenly fails because of DRF changes, we can always force merge it.

Anyway, there might be also other approaches, but that would be part of another PR/discussion.