Won't compile for RP2040 due to pgm_read_byte macro

Re this thread:
https://forums.adafruit.com/viewtopic.php?f=57&t=189849

Can recreate by attempting to compile any library example for any RP2040 target board from earlephilhower core.

Looks like the preproc logic needs some updating to just #include <pgmspace.h> for RP2040:

Lines 39 to 46 in d6db01d

    
           #ifdef __AVR__ 
        
           #include <avr/pgmspace.h> 
        
           #elif defined(ESP8266) || defined(ESP32) 
        
           #include <pgmspace.h> 
        
           #else 
        
           #define pgm_read_byte(addr)                                                    \ 
        
             (*(const unsigned char *)(addr)) ///< PROGMEM workaround for non-AVR 
        
           #endif

erg ok wanna add and also add rp2040 to the CI list?

Fixed with #240

	#ifdef __AVR__
	#include <avr/pgmspace.h>
	#elif defined(ESP8266) \|\| defined(ESP32)
	#include <pgmspace.h>
	#else
	#define pgm_read_byte(addr) \
	((const unsigned char )(addr)) ///< PROGMEM workaround for non-AVR
	#endif