Increase sleep from 10ms to 50ms during set_ptt OFF

Some problems reported on Fake It mode in JTDX with rigs unable to set freq after PTT OFF.

src/rig.c

@@ -2947,7 +2947,7 @@ int HAMLIB_API rig_set_ptt(RIG *rig, vfo_t vfo, ptt_t ptt)
     // some rigs like the FT-2000 with the SCU-17 need just a bit of time to let the relays work
     // can affect fake it mode in WSJT-X when the rig is still in transmit and freq change
     // is requested on a rig that can't change freq on a transmitting VFO
-    if (ptt != RIG_PTT_ON) { hl_usleep(10 * 1000); }
+    if (ptt != RIG_PTT_ON) { hl_usleep(50 * 1000); }
 
     rig->state.cache.ptt = ptt;
     elapsed_ms(&rig->state.cache.time_ptt, HAMLIB_ELAPSED_SET);