Update project to run on Django 5.2

[Razorfang]

DjNRO currently runs on Django 4.2.

As per the Django downloads page, this version will reach end of extended support by April this year.

These changes update the project to use Django 5.2, which will receive extended support until April 2028.

This also fixes https://github.com/REANNZ/djnro/security/dependabot/18 by updating the version of social-auth-app-django to version 5.6. Updating Django to a later version was a requirement for this update.

[vladimir-mencl-eresearch]

Hi @Razorfang ,

Thanks, solid piece of work - and just a few minor points / clarifications.

Well done!

Cheers,
Vlad

[Razorfang]

@vladimir-mencl-eresearch Sorry for the repeated commits regarding the registration salt. I believe I've addressed all your comments now.

[vladimir-mencl-eresearch]

All of my comments have now been addressed - thanks @Razorfang !

[vladimir-mencl-eresearch]

Thanks @Razorfang for this work upgrading the code base to Django 5.2.

I've now reviewed it and I'm happy with what the code looks like.

@ghalse , @zmousm , could you please cast your eyes over this PR as well?

It is just a routine framework upgrade with minor changes, so I hope to be able to merge it within a week, but if I can get another pair of eyes, that would be much appreciated.

Cheers,
Vlad