temp: Constrain social-auth packages for POST issue

[timmc-edx]

See openedx/edx-drf-extensions#561

Merge checklist:

• If adding new checks, followed how_tos/0001-adding-new-checks.rst
• Changelog record added (if needed)
• Documentation updated (not only docstrings) (if needed)
• Commits are squashed

[feanil]

@timmc-edx this change makes sense to mitigate the issue introduced by the upgrade. But it's not clear to me what the long term solution is to fix this? I see that in openedx/edx-drf-extensions#561 there is a proposed solution, is anyone actually working on that?

[timmc-edx]

No one is currently working on it -- our team is finishing up some edxapp containerization work and will likely not be looking into edx-drf-extensions fixes within a month time frame.

But I also haven't looked into the details enough to assess whether the proposed fixes are what we want, or whether we should instead be pushing back on the social-auth changes, etc.