Update the packet_dupe_timeout warning

The warning text was hardcoded at the old 60 second value,
instead of using the config option.

aprsd/threads/rx.py

@@ -112,7 +112,7 @@ class APRSDPluginRXThread(APRSDRXThread):
             else:
                 LOG.warning(
                     f"Packet {packet.from_call}:{packet.msgNo} already tracked "
-                    "but older than 60 seconds. processing.",
+                    f"but older than {CONF.packet_dupe_timeout} seconds. processing.",
                 )
                 pkt_list.rx(packet)
                 self.packet_queue.put(packet)