• Try to ensure IO::Async::OS->socket returns an IO::Socket::IP
  instance for PF_INET or PF_INET6 if it is available
  
• Don't bother testing subsecond loop_once behaviour because most
  loops can't actually do it
  
• Use Future::Utils instead of CPS, removing a dependency
  
• Removed IO::Async::Sequencer
  
• Print a deprecation warning on old loop classes with old timer
  support