fix test that fails every 1st day of the month

apps/explorer/test/explorer/chain_test.exs

@@ -3189,7 +3189,7 @@ defmodule Explorer.ChainTest do
 
       expected_response =
         [token1, token2]
-        |> Enum.sort(&(&1.updated_at < &2.updated_at))
+        |> Enum.sort(&(Timex.to_unix(&1.updated_at) < Timex.to_unix(&2.updated_at)))
         |> Enum.map(& &1.contract_address_hash)
 
       assert Chain.stream_cataloged_token_contract_address_hashes([], &(&2 ++ [&1])) == {:ok, expected_response}