Replace djangorestframework_jwt / drf_jwt with djangorestframework_simplejwt

[mbertrand]

The app has long been using djangorestframework_jwt to handle JSON web token authentication, primarily between micromasters and open. This package has not been updated since 2017. In the short run it is being replaced by a more up-to-date fork (drf_jwt) as part of an upgrade to python 3.11, but in the long run, it would probably be best to use djangorestframework-simplejwt instead - it is recommended in the DRF docs and seems to have more community support.