maintainers: workflows for releases to pypi and rtfd.io

[n2ygk]

I'm still having to manually push new releases to pypi and trigger builds on rtfd.io. We need to get the github actions set up for this.

The Release workflow does push to a pypi repo somewhere but I don't know where to find it:
https://github.com/jazzband/django-oauth-toolkit/blob/37640eeb8b1fda1b9e42d228d35bdbd7a59620b4/.github/workflows/release.yml#L34-L40

@jezdez Can you help us get over the finish line with this?

[jezdez]

There was a data inconsistency in storing the credentials on GitHub that prevented the upload to succeed. I've fixed that now and it should work as expected.

[jezdez]

Oh, regarding ReadTheDocs, it seems as if the webhook was again out of sync with the integration on ReadTheDocs, I've re-enabled it. Not sure what's causing that, but commits to the repo will trigger builds on RTD again now.

[n2ygk]

Keeping this open to confirm all the magic is working when we do the 1.4.1 patch release.

[n2ygk]

Yay it works!