Return 401 for JWT with invalid role

[wolfgangwalther]

A JWT with a role that doesn't exist on the server currently returns a 400 status code. Shouldn't this return a 401 as well, just like all the other JWT errors?

https://github.com/PostgREST/postgrest/blob/465170c7d6c51dace3faf68fbb4040353d5571c0/test/io/test_io.py#L84-L88