Update rtctime.h

As mentioned by Makuna of RTC library

include/rtctime.h

@@ -4,7 +4,6 @@
 #ifdef HAS_RTC
 
 #include <Wire.h> // must be included here so that Arduino library object file references work
-#include <RtcDS3231.h>
 
 #include "globals.h"
 #include "timekeeper.h"
@@ -19,4 +18,4 @@ float get_rtctemp(void);
 
 #endif
 
-#endif // _RTCTIME_H
+#endif // _RTCTIME_H