Add tests for other signing methods

[christiaangoossens]

With the move to joserfc (#150), more signing algorithms are now available.

At least include tests for:

• HS256
• RS256
• ES256
• EdDSA

But if you want, you can do all algorithms listed on https://www.jwt.io/libraries?programming_language=python.

Also resolves #121

[lepture]

Here are all supported algorithms: https://jose.authlib.org/en/guide/algorithms/#json-web-signature