message: Fix PHP 7.4 deprecated argument order for implode()
diff: $conf['reverse_proxy'] = TRUE;
  $conf['reverse_proxy_addresses'] = array_merge(explode(',', getenv('VARNISH_HOSTS')), array('varnish'));
  - $conf['varnish_control_terminal'] = implode($varnish_hosts, " ");
  + $conf['varnish_control_terminal'] = implode(" ", $varnish_hosts);
  $conf['varnish_control_key'] = getenv('VARNISH_SECRET') ?: 'lagoon_default_secret';
  $conf['varnish_version'] = 4;
  }
  