setup rolling window tests

apps/ethereum_jsonrpc/test/ethereum_jsonrpc/rolling_window_test.exs

@@ -10,8 +10,11 @@ defmodule EthereumJSONRPC.RollingWindowTest do
   setup do
     # We set `window_length` to a large time frame so that we can sweep manually to simulate
     # time passing
+    {:ok, pid} =
       RollingWindow.start_link([table: @table, duration: :timer.minutes(120), window_count: 3], name: RollingWindow)
 
+    on_exit(fn -> Process.exit(pid, :normal) end)
+
     :ok
   end