bugfix - unusable pins on pico32 boards (#3573)

According to the technical manual, GPIO 16 + 17 are used for onboard flash, so cannot be used by WLED.

example buildenv:

[env:esp32_pico]
extends = env:esp32dev_qio80
board = pico32

wled00/wled.cpp

@@ -584,6 +584,11 @@ void WLED::setup()
   #else
     DEBUG_PRINTLN(F("PSRAM not used."));
   #endif
+#endif
+#if defined(ARDUINO_ESP32_PICO)
+// special handling for PICO-D4: gpio16+17 are in use for onboard SPI FLASH (not PSRAM)
+managed_pin_type pins[] = { {16, true}, {17, true} };
+pinManager.allocateMultiplePins(pins, sizeof(pins)/sizeof(managed_pin_type), PinOwner::SPI_RAM);
 #endif
 
   //DEBUG_PRINT(F("LEDs inited. heap usage ~"));