Add support for megaavr arch

Author: sandeepmistry

library.properties

@@ -6,5 +6,5 @@ sentence=Arduino Library for the Atmel/Microchip ECC508 and ECC608 crypto chips
 paragraph=
 category=Communication
 url=https://github.com/arduino-libraries/ArduinoECCX08
-architectures=samd
+architectures=samd,megaavr
 includes=ArduinoECCX08.h

src/ECCX08.cpp

@@ -151,7 +151,7 @@ int ECCX08Class::random(byte data[], size_t length)
       return 0;
     }
 
-    int copyLength = min(32, length);
+    int copyLength = min(32, (int)length);
     memcpy(data, response, copyLength);
 
     length -= copyLength;