Added D pin numbers (espressif#4220)

Source: https://wiki.dfrobot.com/FireBeetle_ESP32_IOT_Microcontroller(V3.0)__Supports_Wi-Fi_&_Bluetooth__SKU__DFR0478

Author: gitolicious

Diff for: variants/firebeetle32/pins_arduino.h

@@ -29,6 +29,17 @@ static const uint8_t MOSI  = 23;
 static const uint8_t MISO  = 19;
 static const uint8_t SCK   = 18;
 
+static const uint8_t D0 = 3;
+static const uint8_t D1 = 1;
+static const uint8_t D2 = 25;
+static const uint8_t D3 = 26;
+static const uint8_t D4 = 27;
+static const uint8_t D5 = 9;
+static const uint8_t D6 = 10;
+static const uint8_t D7 = 13;
+static const uint8_t D8 = 5;
+static const uint8_t D9 = 2;
+
 static const uint8_t A0 = 36;
 static const uint8_t A1 = 39;
 static const uint8_t A2 = 34;