fix: fix did update widget Fixes #576

[fstotz]

fix showcase key change crashes app

Description

fixes the issue with changing the key of a showcase widget

`class TestStateful extends StatefulWidget {
const TestStateful({super.key});

@OverRide
State createState() => _TestStatefulState();
}

class _TestStatefulState extends State {
int count = 0;

GlobalKey testKey = GlobalKey();

@OverRide
Widget build(BuildContext context) {
return Column(
mainAxisSize: MainAxisSize.min,
children: [
Counter(count, testKey),
ElevatedButton(
onPressed: () => setState(() {
count++;
testKey = GlobalKey();
}),
child: const Icon(Icons.plus_one))
],
);
}
}

class Counter extends StatelessWidget {
const Counter(this.count, this.testKey,{super.key});

final int count;

final GlobalKey testKey;

@OverRide
Widget build(BuildContext context) {
return Showcase(
key: testKey,
title: "testcount",
child: Text(count.toString()),
);
}
}`

Checklist

• The title of my PR starts with a Conventional Commit prefix (fix:, feat:, docs: etc).
• I have followed the Contributor Guide when preparing my PR.
• I have updated/added tests for ALL new/updated/fixed functionality.
• I have updated/added relevant documentation in docs and added dartdoc comments with ///.
• I have updated/added relevant examples in examples or docs.

Breaking Change?

• Yes, this PR is a breaking change.
• No, this PR is not a breaking change.

Related Issues

#576

[aditya-css]

@fstotz Thank you for raising a PR. Can you please format your code using dart format command.