unify the two github clients used in this repo

[marcoieni]

This repo uses two different GitHub client abstractions:

• team/src/api/github.rs

  Line 39 in 3dabff8

  pub(crate) struct GitHubApi {

• team/src/sync/github/api/mod.rs

  Line 45 in 3dabff8

  client: Client,

We should unify them