Use pin4 for led on T-Beam

esp32_loraprs.ino

@@ -2,7 +2,6 @@
 #include "WiFi.h"
 #include "loraprs_service.h"
 
-#define LED_BUILTIN         2
 #define LED_TOGGLE_PERIOD   1000
 
 //#define BOARD_T_BEAM  // enable for TTG T-Beam board support
@@ -21,6 +20,12 @@
 #pragma message("Configured for server mode")
 #endif
 
+#ifdef BOARD_T_BEAM
+#define LED_BUILTIN         4
+#else
+#define LED_BUILTIN         2
+#endif
+
 void initializeConfig(LoraPrs::Config &cfg) {
   
   // client/server mode switch