Change Elecraft K4 to use TQX instead of TQ to speed up ptt checking time

TQ waits for s-meter hold off time so can time out

rigs/kenwood/kenwood.h

@@ -28,7 +28,7 @@
 #include "token.h"
 #include "idx_builtin.h"
 
-#define BACKEND_VER "20240629"
+#define BACKEND_VER "20240711"
 
 #define EOM_KEN ';'
 #define EOM_TH '\r'