Remove usage of python-jose and settle on PyJWT

[marcospri]

To manage JWKs we introduced jose alongside pyjwt. That's two libraries with very similar features.

We'll settle on jose as it has some features we need and it's based on pyjwt anyway so the APIs are very similar.

A rough plan to migrate would be:

• Move usage of pyjwt outside of the JWTService to it

lms/services/grant_token.py lms/extensions/feature_flags/_helpers.py tests/functional/lti_certification/v13/conftest.py

• Replace usage of pyjwt with jose in JWTService
• Remove pyjwt from the requirements.

[marcospri]

We'll actually do the opposite, remove python-jose and settle on PyJWT as the latter seems to receive more maintenance.

[marcospri]

In h-vialib will replace usage of python-jose for authlib, see: https://github.com/hypothesis/h-vialib/pull/67