Add repos into github_team data sources

[richardpen]

Tested with the built binary, the output looks like:

result = {
  "description" = "This team manages xxxx"
  "id" = "xxxxx"
  "members" = [
    "user_name_1",
  ]
  "name" = "xxxx"
  "node_id" = "xxxxxx="
  "permission" = "pull"
  "privacy" = "closed"
  "repos" = [
    "xxxxx",
  ]
  "slug" = "xxxx"
}