WSJT-X is working with the IC-729 so promotint to stable

https://github.com/Hamlib/Hamlib/issues/429

rigs/icom/ic728.c

@@ -183,7 +183,7 @@ const struct rig_caps ic729_caps =
     .mfg_name =  "Icom",
     .version =  BACKEND_VER ".0",
     .copyright =  "LGPL",
-    .status =  RIG_STATUS_ALPHA,
+    .status =  RIG_STATUS_STABLE,
     .rig_type =  RIG_TYPE_TRANSCEIVER,
     .ptt_type =  RIG_PTT_NONE,
     .dcd_type =  RIG_DCD_NONE,