Define SD_CS_PIN for XIAO (ignores ws_adapters.h)

Author: tyeth

src/Wippersnapper_Boards.h

@@ -276,6 +276,8 @@
 #define USE_TINYUSB
 #define USE_STATUS_LED
 #define STATUS_LED_PIN LED_BUILTIN
+// XIAO S3 Sense Camera addon SD card CS pin GPIO21, or D2/GPIO3 on grove breakout
+#define SD_CS_PIN 21 
 #else
 #warning "Board type not identified within Wippersnapper_Boards.h!"
 #endif