add dispose to files to remove controllers when not used

Frontend/patient_manager/lib/components/builders/BuildFileView.dart

@@ -32,6 +32,12 @@ class _BuildFileViewState extends State<BuildFileView> {
     return path.split("/").last;
   }
 
+  @override
+  void dispose() {
+    pdfViewerController.dispose();
+    super.dispose();
+  }
+
   @override
   Widget build(BuildContext context) {
     // double width = MediaQuery.sizeOf(context).width;