firebase-get-to-know-flutter/step_06 needs to dispose pf the textEditingController #115693
Description
In this codelab, there needs to be a call to dispose of the textEditingController
https://firebase.google.com/codelabs/firebase-get-to-know-flutter#6
https://github.com/flutter/codelabs/blob/main/firebase-get-to-know-flutter/step_06/lib/main.dart
class _GuestBookState extends State {
final _formKey = GlobalKey(debugLabel: '_GuestBookState');
final _controller = TextEditingController();