RS256 support?

[aliak00]

Hey, I've been using jwtd for a while now but since ubuntu 18 + openssl 1.1, it breaks. Is there a chance you can add RS256 algo? :)

[burner]

I have to look if I can do something with https://github.com/shove70/crypto
I don't want to pull openssl or botan for this.

[burner]

PRs are welcome by the way