[WillPopScope] replace deprecated WillPopScope

[theadityaagnihotri]

Description

The Flutter framework has deprecated the usage of WillPopScope constructor in favor of PopScope starting from version v3.12.0-1.0.pre. However, there were still instances of WillPopScope being used in the codebase of the project.

Fixes #270

Type of change

• [x] Refactor (does not change functionality, e.g. code style improvements, linting)

How Has This Been Tested?

There was no alteration in the functionality of the app before or after transitioning from WillPopScope to PopScope.

Checklist:

• [x] My code follows the style guidelines of this project
• [x] I have performed a self-review of my own code
• [x] My changes generate no new warnings
• [x] New and existing unit tests pass locally with my changes
• [x] Any dependent changes have been merged and published in downstream modules
• [x] I have checked my code and corrected any misspellings

Maintainer Checklist

• [ ] closes #xxxx (Replace xxxx with the GitHub issue number)
• [ ] Tag the PR with the appropriate labels

[Aarush-Acharya]

Hey @theadityaagnihotri please respond to this message in order to prove that you are still active

[vrundraval24]

Hey, we are sorry but this branch had some conflicts. And #294 solved the issue #270 without any branch conflicts. So we had to accept it. So we are closing this PR. Good work. We will try to be more active and will wait for your response. Keep contributing. Thanks.