v3.7.2

• Behaviour change:** a binding that cannot be bound (e.g. its port is already in use) is now reported to the caller. startWebServer throws the SocketException instead of returning normally, so a startWebServer cfg app; 0 program exits with a non-zero code and supervisors (systemd Restart=on-failure, Docker restart policies) see the failure. With startWebServerAsync, listening raises the exception instead of never completing (a program blocked on it hung for ever, even on SIGTERM) and the server task is faulted with it. With several bindings, one that fails stops the ones that did start, so startWebServer throws instead of carrying on with only some of them. Stopping the server by cancelling its token still completes cleanly. Adds AsyncResultCell.fail