add dispose to files to remove controllers when not used

Frontend/patient_manager/lib/pages/patientManager.dart

@@ -428,6 +428,13 @@ class _PatientManagerState extends State<PatientManager> {
     }
   }
 
+  @override
+  void dispose() {
+    searchController.dispose();
+    queueDateController.dispose();
+    super.dispose();
+  }
+
   @override
   void initState() {
     patientSearchResults = fetchPatients("abc");