Fix: Remove unused setState causing error after widget disposal

[eliasteeny]

Description

This PR removes unnecessary setState call from InfoPopupWidget that can trigger runtime errors after the widget has been disposed.

Problem

When navigating back while a popup is still visible, the following assertion error is thrown:

'package:flutter/src/widgets/framework.dart': Failed assertion: line 5148 pos 12: '_lifecycleState != _ElementLifecycle.defunct': is not true.

This occurs because setState is being called after the widget has been disposed.

Steps to Reproduce

1. Run the example app.
2. Open the "List Example."
3. Tap any info icon to show a popup.
4. While the popup is displayed, navigate back.
5. Observe the console for the assertion error.

Proposed Solution

Removed the setState call that is invoked after the widget may have already been disposed. Based on testing, this change does not impact the functionality of the widget.