get case info in an async task process

if I understand Tasks correctly, this will spawn a process to go get
the case info and so we won't have to flush or clutter the compiler
process' mailbox

Author: the-mikedavis

test/mint/web_socket/autobahn_test.exs

@@ -15,7 +15,7 @@ defmodule Mint.WebSocket.AutobahnTest do
 
   describe "Autobahn|Testsuite" do
     for case_number <- Range.new(1, AutobahnClient.get_case_count()) do
-      info = AutobahnClient.get_case_info(case_number)
+      info = Task.await(Task.async(fn -> AutobahnClient.get_case_info(case_number) end))
 
       if String.starts_with?(info.id, "9.") do
         @tag :performance