Use OIC instead of Python-Jose

[keaton185]

Context

This package indirectly uses python-jose, which is affected by: GHSA-cjwg-qfpm-7377 which additionally seems to be abandoned by it's maintainers.

Move this package to use OIC to generate the JWK instead.

[keaton185]

@robert-mings for visibility 👀

[dreid]

Introducing a dependency on OIC would cause a pretty significant explosion in transitive dependencies of this package.

https://github.com/CZ-NIC/pyoidc/blob/master/setup.py#L86-L95

And it seems like overkill to bring in a "complete OpenID Connect implementation" just for the couple of JWK related functions actually used.

PyJWT as implemented in #49 in contrast only really depends on the standard library and the well maintained and very popular cryptography package.

[Natim]

Robert is off until June 24th, let's wait for his return to see if we can cut a release.

[robert-mings]

Thanks for the willingness to contribute @keaton185! We've moved ahead with the pyjwt implementation instead of OICthrough this PR.