Fix: Arduino Zero does not define A6. (#34)

By providing different default pins for DE/RE CI build errors can be prevented.

Author: aentinger

src/RS485.h

@@ -36,6 +36,9 @@
 #elif ARDUINO_NANO_RP2040_CONNECT
 #define RS485_DEFAULT_DE_PIN A1
 #define RS485_DEFAULT_RE_PIN A0
+#elif ARDUINO_SAMD_ZERO
+#define RS485_DEFAULT_DE_PIN A4
+#define RS485_DEFAULT_RE_PIN A5
 #else
 #ifndef RS485_DEFAULT_DE_PIN
 #define RS485_DEFAULT_DE_PIN A6