Update pico_rtc.py

Just a little correction of the word "timer" instead of "alarm" for the last test.

micropython/examples/pcf85063a/pico_rtc.py

@@ -85,7 +85,7 @@ print("  >", now)
 print()
 
 print("- clear timer flag")
-rtc.clear_alarm_flag()
+rtc.clear_timer_flag()
 
 print()
 print("tests complete")