Upgrade Flutter SDK in sample app

[Joshuaerinosho]

Release Version:

Release Notes

This PR upgrades the Flutter SDK version in the Example app from 2.7.0 to 2.18.1

Pull request checklist

Please check if your PR fulfills the following requirements:

• Tests for the changes have been added (for bug fixes / features)
• Docs have been reviewed and added / updated if needed (for bug fixes / features)
• The GitHub Actions pass building and linting. Linter returns no warnings or errors.
• The QA checklist below has been completed

Pull request type

Please check the type of change your PR introduces:

• Bugfix
• Feature
• Code style update (formatting, renaming)
• Refactoring (no functional changes, no api changes)
• [ x] Build related changes
• Documentation content changes
• Other (please describe):

What is the current behavior?

Issue Number: N/A
The current Flutter SDK version used in the Example app is 2.7.0

What is the new behavior?

The new Flutter SDK version is 2.18.1

Does this introduce a breaking change?

• Yes
• No

[Meherdeep]

@Joshuaerinosho Thanks for the PR, we will use this with the next release.

[Meherdeep]

Looks good