Add Compatibility for django-allauth v0.55.2

[Dresdn]

This addresses necessary updates and refactoring for compatibility with django-allauth version 0.55.2.

Fixes #534

[Dresdn]

To the reviewers:

Note that this does drop Django 2.2 support, bumps python min to 3.6, Django min to 3.2, and DRF min to 3.13. I did set the min allauth version to 0.55.2 since 0.55.0 introduced all the API changes and there were quick releases after to fix things.

[Dresdn]

Hey @iMerica - Could you take a look at this? Issue #534 is causing issues with the changes django-allauth made, and there are now 3 PRs open.

I know I'm biased, but looking at the different PRs, I think this is the most complete, as we do need to update the dependency requirements.

[iMerica]

Thanks for tagging me. I sometimes miss GitHub notifications.

[Dresdn]

Thanks for all the effort!

[alexei]

@Dresdn @iMerica I appreciate your working on this. What are the plans to releasing the changes?

[iMerica]

Just released @alexei 👍

[alexei]

Great, thanks!