Return  and print a dynamically allocated string that contains the name of every user in a single line.
char *list_users(const User *curr) {
    char *string_arr;
    char *string;
    asprintf(&string_arr, "User List\r\n");
    while (curr != NULL) {
        asprintf(&string, "\t%s\r\n", curr->name);
        curr = curr->next;
    }
    return string;
}