Add Group User

curl --request POST \
  --url https://us.infisical.com/api/v1/groups/{id}/users/{username}

{
  "email": "<string>",
  "username": "<string>",
  "firstName": "<string>",
  "lastName": "<string>",
  "id": "3c90c3cc-0d44-4b50-8888-8dd25736052a"
}