Hide unfinished features in release mode

lib/view/pages/timetable/appointmentDetails.dart

@@ -75,7 +75,7 @@ class AppointmentDetails {
                 leading: const Icon(Icons.person),
                 title: Text("Lehrkraft: (${timetableData.te[0].name}) ${timetableData.te[0].longname}"),
                 trailing: Visibility(
-                  visible: kReleaseMode,
+                  visible: !kReleaseMode,
                   child: IconButton(
                     icon: const Icon(Icons.textsms_outlined),
                     onPressed: () {