add github oauth config to prod

config/prod.secret.exs

@@ -30,6 +30,10 @@ config :entendu, EntenduWeb.Endpoint,
   ],
   secret_key_base: secret_key_base
 
+config :ueberauth, Ueberauth.Strategy.Github.OAuth,
+  client_id: System.get_env("GH_OAUTH_ID"),
+  client_secret: System.get_env("GH_OAUTH_SECRET")
+
 # ## Using releases (Elixir v1.9+)
 #
 # If you are doing OTP releases, you need to instruct Phoenix