HPN-SSH 18.3.0 for OpenSSH 9.6p1

HPN-SSH 18.3.0 incorporates the most recent OpenSSH release, 9.6p1. This version does not introduce any new functionality. However, this release addresses a potential bug that may be encountered when an OpenSSH install is sending data to an HPN-SSH install. In some circumstances, especially at higher RTTs, it is possible that the transfer will enter into a pathological state typified by greatly reduced performance and excessive CPU usage on the sender side. We believe that this might be caused by poor interactions in OpenSSH when large receive windows are advertised to the client. This has been addressed by reducing the maximum size of the window advertised to OpenSSH to 15MB. This is a non-optimal solution especially in high RTT environments. We will be continuing to explore the causes and work towards creating a more performant solution for these situations.