Use new GitHub's Teams API endpoints

[gudmdharalds]

One endpoint of the currently used Teams API endpoints are deprecated:

• Endpoint usage:

  vip-go-ci/github-api.php

  Line 3748 in 2212668

  function vipgoci_github_team_members_get(

• Documentation: https://docs.github.com/en/free-pro-team@latest/rest/reference/teams#list-team-members-legacy

The code should be altered to use the currently recommended endpoint.