Hi,

I noticed type MapClaims of package "gopkg.in/dgrijalva/jwt-go.v3" is used by GinJWTMiddleware.IdentityHandler's parameter, which expose the dependency of gopkg.in/dgrijalva/jwt-go.v3.

I think it would be cleaner that if we replace the dependency with "github.com/appleboy/gin-jwt"'s MapClaims.