Request for Windows Sockets specification version 2.2 instead of 2.0

Thanks to Pavel Mazniker for the report.

src/modbus-tcp.c

@@ -68,7 +68,7 @@ static int _modbus_tcp_init_win32(void)
     /* Initialise Windows Socket API */
     WSADATA wsaData;
 
-    if (WSAStartup(MAKEWORD(2, 0), &wsaData) != 0) {
+    if (WSAStartup(MAKEWORD(2, 2), &wsaData) != 0) {
         fprintf(stderr, "WSAStartup() returned error code %d\n",
                 (unsigned int)GetLastError());
         errno = EIO;