Fix: Set avr and megaavr as the supported architectures.

Author: aentinger

library.properties

@@ -6,5 +6,5 @@ sentence=A port of ArduinoSTL Arduino library.
 paragraph=This library includes important C++ functions, including cout and cin, printf and scanf. It also includes STL containers like vector and algorithm. 
 category=Other
 url=https://github.com/arduino-libraries/Arduino_AVRSTL
-architectures=samd
+architectures=avr,megaavr
 includes=Arduino_AVRSTL.h