Authorization bypass in github.com/dgrijalva/jwt-go

jwt-go allows attackers to bypass intended access restrictions in situations with `[]string{}` for `m["aud"]` (which is allowed by the specification). Because the type assertion fails, "" is the value of aud. This is a security problem if the JWT token is presented to a service that lacks its own audience check. There is no patch available and users of jwt-go are advised to migrate to [golang-jwt](https://github.com/golang-jwt/jwt) at version 3.2.1