curl --request PUT \
  --url https://{cluster}.voucherify.io/management/v1/projects/{projectId}/users/{userId} \
  --header 'Content-Type: application/json' \
  --header 'X-Management-Id: <api-key>' \
  --header 'X-Management-Token: <api-key>' \
  --data '{
  "role": "<string>"
}'

{
  "id": "user_FgEAjOV6RiObJdy36sYynXdqZNiA5gjM",
  "login": "name@youremaildomain.com",
  "email": "name@youremaildomain.com",
  "first_name": "Sammy",
  "last_name": "Jones",
  "projects": {
    "proj_9KeAhZB1": "USER",
    "proj_npnFzPr9": "USER",
    "proj_pEP3NO9s": "USER",
    "proj_zsPdrUIw": "ADMIN"
  },
  "is_owner": false
}