add dispose to files to remove controllers when not used

Frontend/patient_manager/lib/components/patientFiles.dart

@@ -617,6 +617,22 @@ class _PatientFilesState extends State<PatientFiles> {
     }
   }
 
+  @override
+  void dispose() {
+    startDateController.dispose();
+    endDateTextController.dispose();
+    retDateTextController.dispose();
+    selectedFileController.dispose();
+    medicineController.dispose();
+    quantityController.dispose();
+    dosageController.dispose();
+    timesDailyController.dispose();
+    noDaysController.dispose();
+    noRepeatsController.dispose();
+    outputController.dispose();
+    super.dispose();
+  }
+
   @override
   void initState() {
     futueFiles = fetchFiles();