add dispose to files to remove controllers when not used

Frontend/patient_manager/lib/components/popUpMessages/mihSuccessMessage.dart

@@ -93,6 +93,12 @@ class _MIHSuccessMessageState extends State<MIHSuccessMessage> {
     return messageTypes[type];
   }
 
+  @override
+  void dispose() {
+    // TODO: implement dispose
+    super.dispose();
+  }
+
   @override
   void initState() {
     message = widget.successMessage;