Set user role on register

@Andy_Lai , you are right, it doesn’t work in 4.0. A solution presented here How to add custom GraphQL query to Strapi V4 - The IT Solutions doesn’t work either. It would like like this according to that solution:

export const UsersPermissionsRegisterInput =
  (strapi) =>
  ({ nexus }) => ({
    typeDefs: `

    extend input UsersPermissionsRegisterInput {
      role: String!
    }
  `,
  });