migration fix

priv/repo/migrations/20200825061316_move_activity_expirations_to_oban.exs

@@ -13,7 +13,7 @@ def change do
       select: %{id: e.id, activity_id: e.activity_id, scheduled_at: e.scheduled_at}
     )
     |> Pleroma.Repo.stream()
-    |> Enum.each(fn expiration ->
+    |> Stream.each(fn expiration ->
       with {:ok, expires_at} <- DateTime.from_naive(expiration.scheduled_at, "Etc/UTC") do
         Pleroma.Workers.PurgeExpiredActivity.enqueue(%{
           activity_id: FlakeId.to_string(expiration.activity_id),