Update data classes to reflect latest web pixel schema

What changes are you making?

Update the web-pixel data classes to reflect the latest schema and bump the version.

Also updates the PR template to add one more Todo r.e. incrementing the library version

How to test

You can complete a checkout and check the logs section of the sample app (hamburger in settings)

Before you merge

[!IMPORTANT]

[ ] I've added tests to support my implementation

[x] I have read and agree with the Contribution Guidelines.

[x] I have read and agree with the Code of Conduct.

[ ] I've updated the README.

Checklist for releasing a new version

- [x] I have bumped the version number in the [`build.gradle` file](https://github.com/Shopify/checkout-kit-android/blob/main/lib/build.gradle#L17) - [x] I have added a [Changelog](https://github.com/shopify/checkout-sheet-kit-android/blob/main/CHANGELOG.md) entry.

[!TIP] See the Contributing documentation for instructions on how to publish a new version of the library.

Shopify / checkout-sheet-kit-android